Lilian Weng
ML researcher; writes Lil’Log; led OpenAI safety systems; Thinking Machines Lab founding team; back at OpenAI in 2026.
At a glance
Roles
OpenAI and Thinking Machines Lab (before)
See all 2
Also on this page: Key facts · Links · Sources · Related pages
- Lilian Weng is a machine-learning researcher known for Lil’Log, the blog of long survey posts on machine-learning techniques she has written from 2017.
- She joined OpenAI in 2018 on its robotics team, moved to applied AI research in 2021, built and led the safety systems team from 2023 and was VP of research and safety from August 2024 until she left in November 2024.
- In February 2025 she was part of the founding team of Thinking Machines Lab, Mira Murati’s startup.
- She left it in July 2026, citing her health, and days later rejoined OpenAI to lead research on recursive self-improvement.
Key facts
- Lil’Log
- Blog of survey posts, from 20171
- OpenAI
- 2018 to November 2024: robotics, applied AI research (2021), head of safety systems (2023), VP of research and safety (August 2024)2
- Thinking Machines Lab
- Founding team member, February 2025 to July 20263
- OpenAI again
- Rejoined in July 2026 to lead research on recursive self-improvement4
Roles
Before
Part of until Nov 2024
OpenAI (robotics, applied AI research, then head of safety systems and VP of research and safety) source on OpenAI
Part of until Jul 2026
Thinking Machines Lab (founding team) source on Thinking Machines Lab
Links
Sources
- Lil’Log: Archive (opens lilianweng.github.io)
- TechCrunch: OpenAI loses another lead safety researcher, Lilian Weng (2024-11-08) (opens techcrunch.com)
- Wikipedia: Thinking Machines Lab (opens en.wikipedia.org)
- American Bazaar: Weng leaves Thinking Machines to rejoin OpenAI (2026-07-30) (opens americanbazaaronline.com)
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