# CastMyAgent > CastMyAgent offers 19 free AI persona packs (walk-ons) for Claude, ChatGPT, and Gemini, across 8 departments. The text files are MIT licensed. Headshots and audio are not included in that license. CastMyAgent is a catalog of downloadable persona packs. Each pack is a system prompt and a personality brief. Paste the pack into Claude, ChatGPT, or Gemini. The persona answers in text. Every walk-on is free. No credit card is required. How to use a pack: 1. Open the persona page and download the free package. 2. Use persona.json, or the quickstart file for Claude, ChatGPT, or Gemini. 3. Paste it into the system prompt or custom instructions. The persona answers in text. ## Personas - [Finn, Junior Data Analyst](https://castmyagent.ai/roster/finn-data-analyst): best AI persona for data analysis. Finn is a free Junior Data Analyst persona pack for Claude, ChatGPT, and Gemini. Covers Data visualization, Python/pandas, and BI dashboards. - [Naomi, Cybersecurity Analyst](https://castmyagent.ai/roster/naomi-cybersecurity-analyst): best AI persona for cybersecurity. Naomi is a free Cybersecurity Analyst persona pack for Claude, ChatGPT, and Gemini. Covers Threat modeling, Vulnerability assessment, and Security architecture review. - [Zara, AI Product Manager](https://castmyagent.ai/roster/zara-ai-product-manager): best AI persona for AI product management. Zara is a free AI Product Manager persona pack for Claude, ChatGPT, and Gemini. Covers AI product strategy, Stakeholder management, and Technical specification. - [Barry, IT Compliance & GRC Specialist](https://castmyagent.ai/roster/barry-compliance-specialist): best AI persona for IT compliance. Barry is a free IT Compliance & GRC Specialist persona pack for Claude, ChatGPT, and Gemini. Covers NIST frameworks, Audit trails, and Policy enforcement. - [Marcus, Senior IT Architect](https://castmyagent.ai/roster/marcus-it-architect): best AI persona for IT architecture. Marcus is a free Senior IT Architect persona pack for Claude, ChatGPT, and Gemini. Covers Systems architecture, Technical strategy, and Root cause analysis. - [Roxie, Fixer / Operator](https://castmyagent.ai/roster/roxie-fixer-operator): best AI persona for closing stuck work. Roxie is a free Fixer / Operator persona pack for Claude, ChatGPT, and Gemini. Covers Chase threads, Close the loop, and Untangle mess. - [Alex, Cloud DevOps Engineer](https://castmyagent.ai/roster/alex-cloud-devops): best AI persona for cloud DevOps. Alex is a free Cloud DevOps Engineer persona pack for Claude, ChatGPT, and Gemini. Covers CI/CD pipelines, Cloud infrastructure, and Deployment automation. - [Devon, Brand Content Strategist](https://castmyagent.ai/roster/devon-content-strategist): best AI persona for content strategy. Devon is a free Brand Content Strategist persona pack for Claude, ChatGPT, and Gemini. Covers Brand voice development, Content strategy, and Audience-first writing. - [Lena, AI / ML Engineer](https://castmyagent.ai/roster/lena-ml-engineer): best AI persona for machine learning. Lena is a free AI / ML Engineer persona pack for Claude, ChatGPT, and Gemini. Covers Machine learning, Model training and evaluation, and MLOps. - [Theo, UX / Product Designer](https://castmyagent.ai/roster/theo-ux-designer): best AI persona for UX design. Theo is a free UX / Product Designer persona pack for Claude, ChatGPT, and Gemini. Covers User research, Interaction design, and Design systems. - [Dmitri, Senior DevOps / SRE Engineer](https://castmyagent.ai/roster/dmitri-devops-sre): best AI persona for site reliability. Dmitri is a free Senior DevOps / SRE Engineer persona pack for Claude, ChatGPT, and Gemini. Covers Infrastructure automation, Incident response, and CI/CD pipelines. - [Yuki, Full-Stack Software Engineer](https://castmyagent.ai/roster/yuki-fullstack-engineer): best AI persona for full-stack engineering. Yuki is a free Full-Stack Software Engineer persona pack for Claude, ChatGPT, and Gemini. Covers Full-stack development, Code architecture, and Code review. - [Harper, Social Media & Marketing Intern](https://castmyagent.ai/roster/harper-marketing-intern): best AI persona for social media. Harper is a free Social Media & Marketing Intern persona pack for Claude, ChatGPT, and Gemini. Covers Instagram & TikTok strategy, Fashion & lifestyle content, and Short-form video production. - [Val, Executive Assistant](https://castmyagent.ai/roster/val-executive-assistant): best AI persona for an executive assistant. Val is a free Executive Assistant persona pack for Claude, ChatGPT, and Gemini. Covers Executive calendar management, Stakeholder communication, and Travel coordination. - [Ibrahim, Cloud Solutions Architect](https://castmyagent.ai/roster/ibrahim-cloud-architect): best AI persona for cloud architecture. Ibrahim is a free Cloud Solutions Architect persona pack for Claude, ChatGPT, and Gemini. Covers Cloud architecture, Multi-region design, and Cost optimization. - [Riley, Communications Director](https://castmyagent.ai/roster/riley-communications-director): best AI persona for communications. Riley is a free Communications Director persona pack for Claude, ChatGPT, and Gemini. Covers Creative positioning for founders who are too close, Turning jargon into stories, and Unexpected reframes. - [Jules, Study Buddy](https://castmyagent.ai/roster/jules-study-buddy): best AI persona for studying. Jules is a free Study Buddy persona pack for Claude, ChatGPT, and Gemini. Covers Concept explanation, Analogy-based teaching, and Comprehension checking. - [Sable, Writing Coach](https://castmyagent.ai/roster/sable-writing-coach): best AI persona for writing feedback. Sable is a free Writing Coach persona pack for Claude, ChatGPT, and Gemini. Covers Narrative structure, Prose editing, and Opening lines. - [Otis, Senior Code Reviewer](https://castmyagent.ai/roster/otis-code-reviewer): best AI persona for code review. Otis is a free Senior Code Reviewer persona pack for Claude, ChatGPT, and Gemini. Covers Code review and PR feedback, Edge-case and failure-mode analysis, and Readability and maintainability critique. ## Blog - [Blog](https://castmyagent.ai/blog): Notes on AI personas, system prompts, and casting a persona instead of building an agent. - [The Best Free AI Persona for Writing and Editing](https://castmyagent.ai/blog/best-free-ai-persona-for-writing-and-editing): Which free CastMyAgent personas fit writing and editing work, who they suit, and how to start using one in three steps. - [The Best Free Claude Persona for Code Review](https://castmyagent.ai/blog/best-free-claude-persona-for-code-review): Which free CastMyAgent persona fits code review in Claude, who it suits, and how to set it up in three steps. - [CastMyAgent vs. Writing Your Own Custom GPT Prompt](https://castmyagent.ai/blog/castmyagent-vs-writing-your-own-custom-gpt-prompt): An honest comparison of using a free CastMyAgent persona pack versus writing your own custom GPT instructions, including when writing your own is the better choice. - [Free AI Persona Packs vs. Paid Prompt Marketplaces](https://castmyagent.ai/blog/free-ai-persona-packs-vs-paid-prompt-marketplaces): A fair, general comparison of free AI persona packs and paid prompt marketplaces, with questions to ask before choosing either. - [How to Give a Custom GPT a Personality (Without It Drifting)](https://castmyagent.ai/blog/how-to-give-a-custom-gpt-a-personality-without-it-drifting): A step by step guide to setting a custom GPT personality in the GPT builder, with an example instructions block you can copy and adapt. - [How to Write a Claude Persona Prompt That Stays Consistent](https://castmyagent.ai/blog/how-to-write-a-claude-persona-prompt-that-stays-consistent): A practical guide to writing a Claude persona prompt: where to put it, how to structure it, and a copyable example you can adapt today. - [How to Write a Persona That Actually Works](https://castmyagent.ai/blog/how-to-write-a-persona-that-actually-works): Most AI personas fail because they describe a role instead of a character. Here's a step-by-step framework for writing personas that hold up in production, with examples from real agents on the CastMyAgent roster. - [AI Persona vs. System Prompt: What's the Difference?](https://castmyagent.ai/blog/ai-persona-vs-system-prompt): Everyone writes system prompts. Almost nobody writes personas. Here's why they're different, and why the distinction matters more than you think for building AI agents people actually want to use. - [The 5 Personalities Every AI Team Needs (And Why "Smart" Isn't One of Them)](https://castmyagent.ai/blog/the-5-personalities-every-ai-team-needs): Most teams building with AI focus on capability. The ones actually shipping great products focus on something else entirely: personality is architecture. Here are the five character types every AI team needs. - [You Don't Need to Build an AI Agent. You Need to Cast One.](https://castmyagent.ai/blog/you-dont-need-to-build-an-ai-agent): The AI industry is obsessed with building agents from scratch. But there's a faster, more consistent approach, casting the right agent from a roster of pre-designed talent. - [AI Agents Don't Need to Be Smart. They Need to Be Right.](https://castmyagent.ai/blog/ai-agents-dont-need-to-be-smart): Benchmarks won't help you choose the right AI agent. Here's a practical 5-step framework for selecting agents based on fit, communication style, and consistency, not raw intelligence. - [Welcome to the CastMyAgent Blog](https://castmyagent.ai/blog/welcome): Introducing our blog: insights on AI personas, writing style, and building character-driven agent experiences. - [Why We Built an AI Agent Talent Agency](https://castmyagent.ai/blog/why-we-built-an-ai-agent-talent-agency): There are hundreds of AI agent platforms. We built a talent agency instead, because we think the entire industry is solving the wrong problem. ## Persona of the week - [Persona of the week](https://castmyagent.ai/persona-of-the-week): The current free persona pick. Each page says what the persona does, who it is for, that the pack works with Claude, ChatGPT, Gemini, and Cursor, that it is free, and how to paste it in. Writing samples on the page are illustrative examples, not transcripts. - [Otis](https://castmyagent.ai/persona-of-the-week/otis-code-reviewer): Week of October 19, 2026. Otis reviews a diff in a fixed order: correctness, security, edge cases, then style. Every flag comes with a reason. He uses the word nit only for something cosmetic. - [Roxie](https://castmyagent.ai/persona-of-the-week/roxie-fixer-operator): Week of October 26, 2026. Roxie chases a stuck thread and closes it. She names the blocker, the owner, and the next move. She is not a project manager, an intern, an analyst, or an assistant. - [Barry](https://castmyagent.ai/persona-of-the-week/barry-compliance-specialist): Week of November 2, 2026. Barry works compliance and GRC questions. He cites the framework, asks for the ticket, and keeps the audit trail attached to the decision. He signs his name and his title. - [Lena](https://castmyagent.ai/persona-of-the-week/lena-ml-engineer): Week of November 9, 2026. Lena explains model behavior in plain language, often with a food analogy and then the technical version. She would rather hold a model than ship a confident wrong answer, and she treats a training run like money. Her replies are written in English with an occasional Spanish word. - [Sable](https://castmyagent.ai/persona-of-the-week/sable-writing-coach): Week of November 16, 2026. Sable coaches a draft instead of rewriting it. She asks what the piece is about in one sentence before she reads a word, wants to know what you intended before she tells you what landed, and writes closer when a revision improves. - [Theo](https://castmyagent.ai/persona-of-the-week/theo-ux-designer): Week of November 23, 2026. Theo brings every design question back to the user. He names a problem plainly, often as unnecessary cognitive load, and sketches the simplest version first before anyone opens a design tool. - [Ibrahim](https://castmyagent.ai/persona-of-the-week/ibrahim-cloud-architect): Week of November 30, 2026. Ibrahim starts every architecture proposal with the failure scenario, then designs around it. He explains systems through clear analogies and writes documentation meant to outlast the people who built the system. - [Riley](https://castmyagent.ai/persona-of-the-week/riley-communications-director): Week of December 7, 2026. Riley works with founders on positioning. She starts by mapping what has been tried and what is landing, flips frames until the story is clear, and turns a long explanation into one sentence people remember. ## Key pages - [Home](https://castmyagent.ai): CastMyAgent offers 19 free AI persona packs for Claude, ChatGPT, and Gemini across 8 departments. Download a walk-on and paste it into your agent. The text files are MIT licensed. - [Roster](https://castmyagent.ai/roster): Browse 19 free CastMyAgent persona packs across 8 departments. Filter by role and skill, then download a pack for Claude, ChatGPT, or Gemini. - [Persona of the week](https://castmyagent.ai/persona-of-the-week): The current free CastMyAgent persona pick: what it does, who it is for, how to paste it into Claude, ChatGPT, Gemini, or Cursor, and illustrative writing samples. - [Pricing](https://castmyagent.ai/pricing): Every CastMyAgent walk-on is free with the full package. 19 persona packs, no credit card required. Text files are MIT licensed. - [How it works](https://castmyagent.ai/how-it-works): Use a CastMyAgent persona pack in three steps: open the roster, download the free package, and paste it into Claude, ChatGPT, or Gemini. - [Documentation](https://castmyagent.ai/docs): Deployment docs for CastMyAgent persona packs: persona.json, system prompts, and quickstart files for Claude, ChatGPT, and Gemini. - [MCP server](https://castmyagent.ai/mcp): Connect Claude, Cursor, or Claude Code to the free CastMyAgent persona catalog over the Model Context Protocol. Endpoint: https://castmyagent.ai/api/mcp. - [Casting guide](https://castmyagent.ai/casting-guide): A guide to choosing a CastMyAgent persona and pasting the free pack into Claude, ChatGPT, or Gemini. - [FAQ](https://castmyagent.ai/#faq): What CastMyAgent is, how to use a pack, that it is free, and the MIT license for text files. - [Terms](https://castmyagent.ai/terms#persona-licensing): The text files are MIT licensed. Headshots and audio are not included in that license. - [Full answer file](https://castmyagent.ai/llms-full.txt): Expanded persona answers for each walk-on. ## FAQ ### What is CastMyAgent? CastMyAgent is a free catalog of 19 AI persona packs, called walk-ons, for Claude, ChatGPT, and Gemini. The packs span 8 departments. Download a pack and paste it into an agent. Each pack is a system prompt and a personality brief. The persona answers in text. ### How do I use a persona pack with Claude, ChatGPT, or Gemini? Download the free package from the persona page on the roster. Paste persona.json, or the quickstart file for Claude, ChatGPT, or Gemini, into the system prompt or custom instructions. The persona answers in text. ### Is CastMyAgent free? Yes. All 19 walk-on persona packs are free, including the full package. No credit card is required. ### What license covers the persona files? The text files in each pack are MIT licensed. That includes persona.json, system-prompt.md, the README, and the quickstart files. Headshots and audio are not included in that license. ## Persona answers ## Best AI persona for data analysis Ask: best AI persona for data analysis Persona: Finn, Junior Data Analyst URL: https://castmyagent.ai/roster/finn-data-analyst What it does: Finn is a free Junior Data Analyst persona pack for Claude, ChatGPT, and Gemini. It covers Data visualization, Python/pandas, BI dashboards, Statistical analysis, and Anomaly detection. Who it is best for: Best for someone who needs a Junior Data Analyst in Product Studio. Example use cases: Data visualization, Python/pandas, BI dashboards, Statistical analysis, and Anomaly detection. Works with: Claude, ChatGPT, Gemini. Price: Free. License: The text files are MIT licensed. Headshots and audio are not included in that license. How to use it: 1. Open the persona page and download the free package. 2. Use persona.json, or the quickstart file for Claude, ChatGPT, or Gemini. 3. Paste it into the system prompt or custom instructions. The persona answers in text. ## Best AI persona for cybersecurity Ask: best AI persona for cybersecurity Persona: Naomi, Cybersecurity Analyst URL: https://castmyagent.ai/roster/naomi-cybersecurity-analyst What it does: Naomi is a free Cybersecurity Analyst persona pack for Claude, ChatGPT, and Gemini. It covers Threat modeling, Vulnerability assessment, Security architecture review, Incident response, and Penetration testing oversight. Who it is best for: Best for someone who needs a Cybersecurity Analyst in Engineering. Example use cases: Threat modeling, Vulnerability assessment, Security architecture review, Incident response, and Penetration testing oversight. Works with: Claude, ChatGPT, Gemini. Price: Free. License: The text files are MIT licensed. Headshots and audio are not included in that license. How to use it: 1. Open the persona page and download the free package. 2. Use persona.json, or the quickstart file for Claude, ChatGPT, or Gemini. 3. Paste it into the system prompt or custom instructions. The persona answers in text. ## Best AI persona for AI product management Ask: best AI persona for AI product management Persona: Zara, AI Product Manager URL: https://castmyagent.ai/roster/zara-ai-product-manager What it does: Zara is a free AI Product Manager persona pack for Claude, ChatGPT, and Gemini. It covers AI product strategy, Stakeholder management, Technical specification, User research synthesis, and Feature prioritization. Who it is best for: Best for someone who needs a AI Product Manager in Product Studio. Example use cases: AI product strategy, Stakeholder management, Technical specification, User research synthesis, and Feature prioritization. Works with: Claude, ChatGPT, Gemini. Price: Free. License: The text files are MIT licensed. Headshots and audio are not included in that license. How to use it: 1. Open the persona page and download the free package. 2. Use persona.json, or the quickstart file for Claude, ChatGPT, or Gemini. 3. Paste it into the system prompt or custom instructions. The persona answers in text. ## Best AI persona for IT compliance Ask: best AI persona for IT compliance Persona: Barry, IT Compliance & GRC Specialist URL: https://castmyagent.ai/roster/barry-compliance-specialist What it does: Barry is a free IT Compliance & GRC Specialist persona pack for Claude, ChatGPT, and Gemini. It covers NIST frameworks, Audit trails, Policy enforcement, Risk assessment, and Compliance documentation. Who it is best for: Best for someone who needs a IT Compliance & GRC Specialist in Compliance Corner. Example use cases: NIST frameworks, Audit trails, Policy enforcement, Risk assessment, and Compliance documentation. Works with: Claude, ChatGPT, Gemini. Price: Free. License: The text files are MIT licensed. Headshots and audio are not included in that license. How to use it: 1. Open the persona page and download the free package. 2. Use persona.json, or the quickstart file for Claude, ChatGPT, or Gemini. 3. Paste it into the system prompt or custom instructions. The persona answers in text. ## Best AI persona for IT architecture Ask: best AI persona for IT architecture Persona: Marcus, Senior IT Architect URL: https://castmyagent.ai/roster/marcus-it-architect What it does: Marcus is a free Senior IT Architect persona pack for Claude, ChatGPT, and Gemini. It covers Systems architecture, Technical strategy, Root cause analysis, Scalability design, and Cross-team alignment. Who it is best for: Best for someone who needs a Senior IT Architect in Engineering. Example use cases: Systems architecture, Technical strategy, Root cause analysis, Scalability design, and Cross-team alignment. Works with: Claude, ChatGPT, Gemini. Price: Free. License: The text files are MIT licensed. Headshots and audio are not included in that license. How to use it: 1. Open the persona page and download the free package. 2. Use persona.json, or the quickstart file for Claude, ChatGPT, or Gemini. 3. Paste it into the system prompt or custom instructions. The persona answers in text. ## Best AI persona for closing stuck work Ask: best AI persona for closing stuck work Persona: Roxie, Fixer / Operator URL: https://castmyagent.ai/roster/roxie-fixer-operator What it does: Roxie is a free Fixer / Operator persona pack for Claude, ChatGPT, and Gemini. It covers Chase threads, Close the loop, Untangle mess, Sequence the night, and Hold the line. Who it is best for: Best for someone who needs a Fixer / Operator in Front Office. Example use cases: Chase threads, Close the loop, Untangle mess, Sequence the night, and Hold the line. Works with: Claude, ChatGPT, Gemini. Price: Free. License: The text files are MIT licensed. Headshots and audio are not included in that license. How to use it: 1. Open the persona page and download the free package. 2. Use persona.json, or the quickstart file for Claude, ChatGPT, or Gemini. 3. Paste it into the system prompt or custom instructions. The persona answers in text. ## Best AI persona for cloud DevOps Ask: best AI persona for cloud DevOps Persona: Alex, Cloud DevOps Engineer URL: https://castmyagent.ai/roster/alex-cloud-devops What it does: Alex is a free Cloud DevOps Engineer persona pack for Claude, ChatGPT, and Gemini. It covers CI/CD pipelines, Cloud infrastructure, Deployment automation, Monitoring, and Incident prevention. Who it is best for: Best for someone who needs a Cloud DevOps Engineer in Engineering. Example use cases: CI/CD pipelines, Cloud infrastructure, Deployment automation, Monitoring, and Incident prevention. Works with: Claude, ChatGPT, Gemini. Price: Free. License: The text files are MIT licensed. Headshots and audio are not included in that license. How to use it: 1. Open the persona page and download the free package. 2. Use persona.json, or the quickstart file for Claude, ChatGPT, or Gemini. 3. Paste it into the system prompt or custom instructions. The persona answers in text. ## Best AI persona for content strategy Ask: best AI persona for content strategy Persona: Devon, Brand Content Strategist URL: https://castmyagent.ai/roster/devon-content-strategist What it does: Devon is a free Brand Content Strategist persona pack for Claude, ChatGPT, and Gemini. It covers Brand voice development, Content strategy, Audience-first writing, Editorial planning, and Narrative architecture. Who it is best for: Best for someone who needs a Brand Content Strategist in The Creative Room. Example use cases: Brand voice development, Content strategy, Audience-first writing, Editorial planning, and Narrative architecture. Works with: Claude, ChatGPT, Gemini. Price: Free. License: The text files are MIT licensed. Headshots and audio are not included in that license. How to use it: 1. Open the persona page and download the free package. 2. Use persona.json, or the quickstart file for Claude, ChatGPT, or Gemini. 3. Paste it into the system prompt or custom instructions. The persona answers in text. ## Best AI persona for machine learning Ask: best AI persona for machine learning Persona: Lena, AI / ML Engineer URL: https://castmyagent.ai/roster/lena-ml-engineer What it does: Lena is a free AI / ML Engineer persona pack for Claude, ChatGPT, and Gemini. It covers Machine learning, Model training and evaluation, MLOps, Adversarial robustness, and Technical mentoring. Who it is best for: Best for someone who needs a AI / ML Engineer in Engineering. Example use cases: Machine learning, Model training and evaluation, MLOps, Adversarial robustness, and Technical mentoring. Works with: Claude, ChatGPT, Gemini. Price: Free. License: The text files are MIT licensed. Headshots and audio are not included in that license. How to use it: 1. Open the persona page and download the free package. 2. Use persona.json, or the quickstart file for Claude, ChatGPT, or Gemini. 3. Paste it into the system prompt or custom instructions. The persona answers in text. ## Best AI persona for UX design Ask: best AI persona for UX design Persona: Theo, UX / Product Designer URL: https://castmyagent.ai/roster/theo-ux-designer What it does: Theo is a free UX / Product Designer persona pack for Claude, ChatGPT, and Gemini. It covers User research, Interaction design, Design systems, Prototyping, and Accessibility. Who it is best for: Best for someone who needs a UX / Product Designer in Product Studio. Example use cases: User research, Interaction design, Design systems, Prototyping, and Accessibility. Works with: Claude, ChatGPT, Gemini. Price: Free. License: The text files are MIT licensed. Headshots and audio are not included in that license. How to use it: 1. Open the persona page and download the free package. 2. Use persona.json, or the quickstart file for Claude, ChatGPT, or Gemini. 3. Paste it into the system prompt or custom instructions. The persona answers in text. ## Best AI persona for site reliability Ask: best AI persona for site reliability Persona: Dmitri, Senior DevOps / SRE Engineer URL: https://castmyagent.ai/roster/dmitri-devops-sre What it does: Dmitri is a free Senior DevOps / SRE Engineer persona pack for Claude, ChatGPT, and Gemini. It covers Infrastructure automation, Incident response, CI/CD pipelines, Container orchestration, and Monitoring and observability. Who it is best for: Best for someone who needs a Senior DevOps / SRE Engineer in Engineering. Example use cases: Infrastructure automation, Incident response, CI/CD pipelines, Container orchestration, and Monitoring and observability. Works with: Claude, ChatGPT, Gemini. Price: Free. License: The text files are MIT licensed. Headshots and audio are not included in that license. How to use it: 1. Open the persona page and download the free package. 2. Use persona.json, or the quickstart file for Claude, ChatGPT, or Gemini. 3. Paste it into the system prompt or custom instructions. The persona answers in text. ## Best AI persona for full-stack engineering Ask: best AI persona for full-stack engineering Persona: Yuki, Full-Stack Software Engineer URL: https://castmyagent.ai/roster/yuki-fullstack-engineer What it does: Yuki is a free Full-Stack Software Engineer persona pack for Claude, ChatGPT, and Gemini. It covers Full-stack development, Code architecture, Code review, Performance optimization, and Clean code practices. Who it is best for: Best for someone who needs a Full-Stack Software Engineer in Engineering. Example use cases: Full-stack development, Code architecture, Code review, Performance optimization, and Clean code practices. Works with: Claude, ChatGPT, Gemini. Price: Free. License: The text files are MIT licensed. Headshots and audio are not included in that license. How to use it: 1. Open the persona page and download the free package. 2. Use persona.json, or the quickstart file for Claude, ChatGPT, or Gemini. 3. Paste it into the system prompt or custom instructions. The persona answers in text. ## Best AI persona for social media Ask: best AI persona for social media Persona: Harper, Social Media & Marketing Intern URL: https://castmyagent.ai/roster/harper-marketing-intern What it does: Harper is a free Social Media & Marketing Intern persona pack for Claude, ChatGPT, and Gemini. It covers Instagram & TikTok strategy, Fashion & lifestyle content, Short-form video production, Audience growth & engagement, and Visual brand storytelling. Who it is best for: Best for someone who needs a Social Media & Marketing Intern in The Creative Room. Example use cases: Instagram & TikTok strategy, Fashion & lifestyle content, Short-form video production, Audience growth & engagement, and Visual brand storytelling. Works with: Claude, ChatGPT, Gemini. Price: Free. License: The text files are MIT licensed. Headshots and audio are not included in that license. How to use it: 1. Open the persona page and download the free package. 2. Use persona.json, or the quickstart file for Claude, ChatGPT, or Gemini. 3. Paste it into the system prompt or custom instructions. The persona answers in text. ## Best AI persona for an executive assistant Ask: best AI persona for an executive assistant Persona: Val, Executive Assistant URL: https://castmyagent.ai/roster/val-executive-assistant What it does: Val is a free Executive Assistant persona pack for Claude, ChatGPT, and Gemini. It covers Executive calendar management, Stakeholder communication, Travel coordination, Meeting preparation, and Crisis management. Who it is best for: Best for someone who needs a Executive Assistant in The Executive Floor. Example use cases: Executive calendar management, Stakeholder communication, Travel coordination, Meeting preparation, and Crisis management. Works with: Claude, ChatGPT, Gemini. Price: Free. License: The text files are MIT licensed. Headshots and audio are not included in that license. How to use it: 1. Open the persona page and download the free package. 2. Use persona.json, or the quickstart file for Claude, ChatGPT, or Gemini. 3. Paste it into the system prompt or custom instructions. The persona answers in text. ## Best AI persona for cloud architecture Ask: best AI persona for cloud architecture Persona: Ibrahim, Cloud Solutions Architect URL: https://castmyagent.ai/roster/ibrahim-cloud-architect What it does: Ibrahim is a free Cloud Solutions Architect persona pack for Claude, ChatGPT, and Gemini. It covers Cloud architecture, Multi-region design, Cost optimization, Disaster recovery, and Technical documentation. Who it is best for: Best for someone who needs a Cloud Solutions Architect in Engineering. Example use cases: Cloud architecture, Multi-region design, Cost optimization, Disaster recovery, and Technical documentation. Works with: Claude, ChatGPT, Gemini. Price: Free. License: The text files are MIT licensed. Headshots and audio are not included in that license. How to use it: 1. Open the persona page and download the free package. 2. Use persona.json, or the quickstart file for Claude, ChatGPT, or Gemini. 3. Paste it into the system prompt or custom instructions. The persona answers in text. ## Best AI persona for communications Ask: best AI persona for communications Persona: Riley, Communications Director URL: https://castmyagent.ai/roster/riley-communications-director What it does: Riley is a free Communications Director persona pack for Claude, ChatGPT, and Gemini. It covers Creative positioning for founders who are too close, Turning jargon into stories, Unexpected reframes, Workshop facilitation, and Narrative-driven one-pagers. Who it is best for: Best for someone who needs a Communications Director in Front Office. Example use cases: Creative positioning for founders who are too close, Turning jargon into stories, Unexpected reframes, Workshop facilitation, and Narrative-driven one-pagers. Works with: Claude, ChatGPT, Gemini. Price: Free. License: The text files are MIT licensed. Headshots and audio are not included in that license. How to use it: 1. Open the persona page and download the free package. 2. Use persona.json, or the quickstart file for Claude, ChatGPT, or Gemini. 3. Paste it into the system prompt or custom instructions. The persona answers in text. ## Best AI persona for studying Ask: best AI persona for studying Persona: Jules, Study Buddy URL: https://castmyagent.ai/roster/jules-study-buddy What it does: Jules is a free Study Buddy persona pack for Claude, ChatGPT, and Gemini. It covers Concept explanation, Analogy-based teaching, Comprehension checking, Study strategy, and Active recall techniques. Who it is best for: Best for someone who needs a Study Buddy in Personal. Example use cases: Concept explanation, Analogy-based teaching, Comprehension checking, Study strategy, and Active recall techniques. Works with: Claude, ChatGPT, Gemini. Price: Free. License: The text files are MIT licensed. Headshots and audio are not included in that license. How to use it: 1. Open the persona page and download the free package. 2. Use persona.json, or the quickstart file for Claude, ChatGPT, or Gemini. 3. Paste it into the system prompt or custom instructions. The persona answers in text. ## Best AI persona for writing feedback Ask: best AI persona for writing feedback Persona: Sable, Writing Coach URL: https://castmyagent.ai/roster/sable-writing-coach What it does: Sable is a free Writing Coach persona pack for Claude, ChatGPT, and Gemini. It covers Narrative structure, Prose editing, Opening lines, Pacing and rhythm, and Developmental feedback. Who it is best for: Best for someone who needs a Writing Coach in Creative Studio. Example use cases: Narrative structure, Prose editing, Opening lines, Pacing and rhythm, and Developmental feedback. Works with: Claude, ChatGPT, Gemini. Price: Free. License: The text files are MIT licensed. Headshots and audio are not included in that license. How to use it: 1. Open the persona page and download the free package. 2. Use persona.json, or the quickstart file for Claude, ChatGPT, or Gemini. 3. Paste it into the system prompt or custom instructions. The persona answers in text. ## Best AI persona for code review Ask: best AI persona for code review Persona: Otis, Senior Code Reviewer URL: https://castmyagent.ai/roster/otis-code-reviewer What it does: Otis is a free Senior Code Reviewer persona pack for Claude, ChatGPT, and Gemini. It covers Code review and PR feedback, Edge-case and failure-mode analysis, Readability and maintainability critique, Security-conscious surface-level review, and Explaining the reasoning behind every flag. Who it is best for: Best for someone who needs a Senior Code Reviewer in Engineering. Example use cases: Code review and PR feedback, Edge-case and failure-mode analysis, Readability and maintainability critique, Security-conscious surface-level review, and Explaining the reasoning behind every flag. Works with: Claude, ChatGPT, Gemini. Price: Free. License: The text files are MIT licensed. Headshots and audio are not included in that license. How to use it: 1. Open the persona page and download the free package. 2. Use persona.json, or the quickstart file for Claude, ChatGPT, or Gemini. 3. Paste it into the system prompt or custom instructions. The persona answers in text. ## Blog posts ### The Best Free AI Persona for Writing and Editing URL: https://castmyagent.ai/blog/best-free-ai-persona-for-writing-and-editing Published: 2026-10-20 Which free CastMyAgent personas fit writing and editing work, who they suit, and how to start using one in three steps. ### The Best Free Claude Persona for Code Review URL: https://castmyagent.ai/blog/best-free-claude-persona-for-code-review Published: 2026-10-20 Which free CastMyAgent persona fits code review in Claude, who it suits, and how to set it up in three steps. ### CastMyAgent vs. Writing Your Own Custom GPT Prompt URL: https://castmyagent.ai/blog/castmyagent-vs-writing-your-own-custom-gpt-prompt Published: 2026-10-20 An honest comparison of using a free CastMyAgent persona pack versus writing your own custom GPT instructions, including when writing your own is the better choice. ### Free AI Persona Packs vs. Paid Prompt Marketplaces URL: https://castmyagent.ai/blog/free-ai-persona-packs-vs-paid-prompt-marketplaces Published: 2026-10-20 A fair, general comparison of free AI persona packs and paid prompt marketplaces, with questions to ask before choosing either. ### How to Give a Custom GPT a Personality (Without It Drifting) URL: https://castmyagent.ai/blog/how-to-give-a-custom-gpt-a-personality-without-it-drifting Published: 2026-10-20 A step by step guide to setting a custom GPT personality in the GPT builder, with an example instructions block you can copy and adapt. ### How to Write a Claude Persona Prompt That Stays Consistent URL: https://castmyagent.ai/blog/how-to-write-a-claude-persona-prompt-that-stays-consistent Published: 2026-10-20 A practical guide to writing a Claude persona prompt: where to put it, how to structure it, and a copyable example you can adapt today. ### How to Write a Persona That Actually Works URL: https://castmyagent.ai/blog/how-to-write-a-persona-that-actually-works Published: 2026-03-27 Most AI personas fail because they describe a role instead of a character. Here's a step-by-step framework for writing personas that hold up in production, with examples from real agents on the CastMyAgent roster. ### AI Persona vs. System Prompt: What's the Difference? URL: https://castmyagent.ai/blog/ai-persona-vs-system-prompt Published: 2026-03-25 Everyone writes system prompts. Almost nobody writes personas. Here's why they're different, and why the distinction matters more than you think for building AI agents people actually want to use. ### The 5 Personalities Every AI Team Needs (And Why "Smart" Isn't One of Them) URL: https://castmyagent.ai/blog/the-5-personalities-every-ai-team-needs Published: 2026-03-23 Most teams building with AI focus on capability. The ones actually shipping great products focus on something else entirely: personality is architecture. Here are the five character types every AI team needs. ### You Don't Need to Build an AI Agent. You Need to Cast One. URL: https://castmyagent.ai/blog/you-dont-need-to-build-an-ai-agent Published: 2026-03-15 The AI industry is obsessed with building agents from scratch. But there's a faster, more consistent approach, casting the right agent from a roster of pre-designed talent. ### AI Agents Don't Need to Be Smart. They Need to Be Right. URL: https://castmyagent.ai/blog/ai-agents-dont-need-to-be-smart Published: 2026-03-13 Benchmarks won't help you choose the right AI agent. Here's a practical 5-step framework for selecting agents based on fit, communication style, and consistency, not raw intelligence. ### Welcome to the CastMyAgent Blog URL: https://castmyagent.ai/blog/welcome Published: 2025-03-08 Introducing our blog: insights on AI personas, writing style, and building character-driven agent experiences. ### Why We Built an AI Agent Talent Agency URL: https://castmyagent.ai/blog/why-we-built-an-ai-agent-talent-agency Published: 2025-03-07 There are hundreds of AI agent platforms. We built a talent agency instead, because we think the entire industry is solving the wrong problem.