Alexei "Lex" Fridman (/ˈfriːdmən/; born 15 August 1983) is an American computer scientist and podcaster. Since 2018, he has hosted the Lex Fridman Podcast, where he interviews notable figures from various fields such as science, technology, sports, the arts, and politics.

Fridman rose to prominence in 2019 after Elon Musk praised a study Fridman authored at MIT, which concluded that drivers remained focused while using Tesla's semi-autonomous driving system. The study was not peer-reviewed and was criticized by AI experts. That year Fridman transitioned to an unpaid role at MIT AgeLab, and since 2022 has worked as a research scientist at the MIT Laboratory for Information and Decision Systems (LIDS). As of February 2024, Fridman lives in Texas and is employed at MIT.

Fridman was born in Chkalovsk, Tajik Soviet Socialist Republic, and grew up in Moscow. He is Jewish. His father, Alexander Fridman, is a plasma physicist and professor at Drexel University. His brother Gregory was also a professor at Drexel.

When he was about 11, soon after the collapse of the Soviet Union, Fridman's family moved from Russia to the Chicago area. He attended Neuqua Valley High School in Naperville, Illinois. He then went on to obtain B.S. and M.S. degrees in computer science at Drexel University in 2010, and completed his Ph.D. in electrical and computer engineering at Drexel in 2014. His PhD dissertation, Learning of Identity from Behavioral Biometrics for Active Authentication, was completed under the advisement of engineering educators Moshe Kam and Steven Weber and sought to "investigate the problem of active authentication on desktop computers and mobile devices".

In 2014, he spent six months at Google continuing his dissertation work on the use of AI for identity authentication and participated in "deep learning efforts for large-scale behavior-based authentication". In 2015, he moved to MIT's AgeLab as a research scientist where he worked on "psychology and big-data analytics to understand driver behavior." At AgeLab, Fridman led a set of computer engineers in developing learning algorithms for semi-autonomous vehicles in collaboration with Toyota. In 2017, a paper co-authored by Fridman was among the recipients of a "Best Paper" award at the Conference on Human Factors in Computing Systems, a high ranking conference in the field of human–computer interaction. The following year another paper he co-authored would be among those given an "honorable mention". Fridman also guest lectured at his alma mater, Drexel.

In 2019, Fridman published a non-peer-reviewed study about Tesla Autopilot finding that drivers using semi-autonomous vehicles stayed focused, contrasting with established research on how humans interact with automated systems. Following his Tesla Autopilot study, Fridman was flown to Tesla offices for an interview with Elon Musk. Fridman's study on Tesla Autopilot was criticized for its methodology and small sample size by Missy Cummings, a professor at Duke University and advisor for the National Highway Traffic Safety Administration, who described it as "deeply flawed". AI researcher Anima Anandkumar suggested Fridman should submit his study for peer review before seeking press coverage. Following the interview with Musk, viewings of his podcast episodes increased significantly. The study was later removed from MIT's website.

Following the publication of the study, he left AgeLab and took up an unpaid role in MIT's Department of Aeronautics and Astronautics. As of 2022, he is a research scientist at the MIT Laboratory for Information and Decision Systems (LIDS). He remains in that position, and also conducts research for the Center for Complex Engineering Systems, a collaboration between MIT and King Abdulaziz City for Science and Technology (KACST).

Fridman began his podcast in 2018. It was originally titled The Artificial Intelligence Podcast, but changed to The Lex Fridman Podcast in 2020. In 2024, the Boston Globe reported that the podcast had attracted 3.6 million subscribers.