# Anastasios Angelopoulos

> Anastasios Nikolas Angelopoulos is the co-founder and CEO of Arena, the San Francisco AI-evaluation company that grew out of UC Berkeley's Chatbot Arena research project. Trained in electrical engineering, machine learning, and theoretical statistics at Stanford and Berkeley, he has built a career around making powerful black-box systems measurable and reliable. Arena turns millions of real-world comparisons into public leaderboards and commercial evaluation tools, while Angelopoulos continues to publish research on conformal prediction, statistical inference, and model evaluation.

- **Role:** Co-founder and CEO at Arena
- **Organizations:** Arena, University of California, Berkeley, Stanford University, Google DeepMind, Debate Team USA
- **Education:** B.S. in Electrical Engineering, Stanford University, Ph.D. in Electrical Engineering and Computer Sciences, University of California, Berkeley
- **Known for:** Co-created Chatbot Arena, an open human-preference platform whose rankings are followed by major AI model developers., Co-authored the ICML 2024 paper Chatbot Arena: An Open Platform for Evaluating LLMs by Human Preference., Co-authored Prediction-Powered Inference, published in Science in 2023.

## Career timeline

- **2012-2016** — Competed as a debater, becoming a national champion and a member of Debate Team USA.
- **2016-2019** — Studied electrical engineering at Stanford University with advisers Gordon Wetzstein and Stephen P. Boyd.
- **2019-2024** — Completed a Ph.D. in EECS at UC Berkeley, advised by Michael I. Jordan and Jitendra Malik, focusing on theoretical statistics and reliable machine learning.
- **2023** — Helped develop Chatbot Arena at Berkeley's Sky Computing Lab as an open platform for evaluating language models through blind human preference votes.
- **2023** — Co-authored Prediction-Powered Inference, published in Science, and Conformal Prediction: A Gentle Introduction.
- **2024** — The Chatbot Arena paper appeared at ICML; Angelopoulos also became a UC Berkeley postdoctoral scholar working with Ion Stoica and was a student researcher at Google DeepMind.
- **2024-present** — Serves as co-founder and CEO of Arena in San Francisco.
- **2025** — Arena announced a $100 million seed round and launched its commercial AI Evaluations product in September.
- **2026** — Arena announced a $150 million Series A led by Felicis and UC Investments, rebranded from LMArena to Arena, and expanded its evaluation work across additional modalities and agentic systems.

## Achievements

- Co-created Chatbot Arena, an open human-preference platform whose rankings are followed by major AI model developers.
- Co-authored the ICML 2024 paper Chatbot Arena: An Open Platform for Evaluating LLMs by Human Preference.
- Co-authored Prediction-Powered Inference, published in Science in 2023.
- Co-authored Conformal Prediction: A Gentle Introduction and the forthcoming Cambridge University Press book Theoretical Foundations of Conformal Prediction.
- Received the NSF Graduate Research Fellowship, Berkeley Fellowship, Leon O. Chua Department Award, and Sequoia Open Source Software Fellowship.
- Received Stanford's Frederick Emmons Terman Engineering Scholastic Award and graduated with departmental distinction; was elected to Phi Beta Kappa and Tau Beta Pi.
- Led Arena as it announced $250 million in cumulative funding across its 2025 seed and 2026 Series A rounds.

## Latest updates

- **2026-07** — Arena introduced additional product and research updates, including factuality-aware rankings and AutoEval scoring, while continuing to publish leaderboard data and methodology.
- **2026-06** — Angelopoulos announced that Arena had reached a $100 million annualized revenue run rate eight months after launching its enterprise offering; the company also introduced Agent Mode and published its Agent Arena methodology.
- **2026-02** — Arena launched its new brand around the mission of measuring intelligence in the real world; Angelopoulos said he planned to devote more time to evaluation science and AI reliability.
- **2026-01** — Arena announced a $150 million Series A led by Felicis and UC Investments, following its $100 million seed round in 2025.

## Links

- Website: https://angelopoulos.ai/
- LinkedIn: https://www.linkedin.com/in/ml-angelopoulos
- Twitter/X: https://x.com/ml_angelopoulos
- GitHub: https://github.com/aangelopoulos

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Profile page: https://yespress.io/anastasios-angelopoulos
Published by YesPress — https://yespress.io
Last updated: 2026-08-17