Dan Hendrycks

American machine-learning researcher known for widely used benchmarks and for AI-safety advocacy; he co-founded the Center for AI SafetyCenter for AI Safety, prop. n.: A San Francisco nonprofit that studies how advanced AI could lead to disaster and how to prevent it. In 2023 it gathered signatures for a one-sentence warning that AI could threaten human extinction. (CAIS) in 2022 and directs it. As a student, with Kevin Gimpel, he introduced the GELUGELU, abbr.: A smooth version of the ReLU rule, used in models such as BERT and GPT: it keeps large positive values, removes large negative ones, and blends softly in between. activation (2016), later standard in transformerstransformer, n.: The design behind today's chatbots and much of modern AI. It handles text by letting every word look at every other word and decide which of them matter for understanding it., and a widely used baseline for detecting out-of-distributionout-of-distribution, adj.: Describes inputs that differ from anything an AI system saw in training — like a model trained on daytime photos facing a night scene — where its answers become less reliable. inputs. During his doctorate at the University of California, Berkeley, he led the creation of benchmarks that became fixtures of model evaluation, including MMLUMMLU, prop. n.: A giant multiple-choice exam for AI covering 57 subjects, from school math and history to law and medicine; for years it was the most quoted test of a model's general knowledge. (2020) and MATHMATH, prop. n.: A set of 12,500 problems from high-school math competitions, each with a full worked solution, used to test language models on genuinely challenging mathematics. (2021), and later, with Scale AIScale AI, prop. n.: A company that pays large numbers of people to label examples, write model answers and grade chatbot replies, producing the data AI developers train and test on. Meta bought nearly half of it in 2025., Humanity's Last ExamHumanity's Last Exam, prop. n.: A test of 2,500 extremely hard questions with definite answers, written by about a thousand experts worldwide and billed as the last academic exam AI would need; at launch, top models scored under 10%. (2025). Through CAIS he organized the 2023 Statement on AI RiskStatement on AI Risk, prop. n.: A one-sentence public statement from May 2023, signed by hundreds of leading AI scientists and company heads, declaring that guarding against the chance of AI wiping out humanity should rank as a priority for the whole world., and its advocacy arm co-sponsored California's SB 1047SB 1047, prop. n.: A 2024 California bill that would have required makers of the biggest AI models to adopt safety plans and take care to prevent catastrophes. It passed the legislature, but the governor vetoed it.. With Eric Schmidt and Alexandr Wang he wrote 'Superintelligence Strategy' (2025), which proposed the deterrence regime of Mutual Assured AI MalfunctionMutual Assured AI Malfunction, n.: A proposed deterrence strategy in which any country racing for overwhelming AI dominance would expect rivals to sabotage its AI projects, so none tries, much as with nuclear deterrence.. He has also advised xAIxAI, prop. n.: An artificial intelligence company founded by Elon Musk in 2023 that makes the Grok chatbot. It is now part of Musk's rocket company, SpaceX. and Scale AI on safety.