Bjorn Mikhail Poonen (born July 27, 1968, in Boston, Massachusetts) is a mathematician, four-time Putnam Competition winner, and a Distinguished Professor in Science in the Department of Mathematics at the Massachusetts Institute of Technology.

[1] His research is primarily in arithmetic geometry, but he has occasionally published in other subjects such as probability[2] and computer science.

[4][5] He is the founding managing editor of the journal Algebra & Number Theory,[6] and serves also on the editorial boards of Involve: A Journal of Mathematics[7] and the A K Peters Research Notes in Mathematics book series.

He then studied under Kenneth Alan Ribet at the University of California, Berkeley, completing a PhD there in 1994.

[8] He has also held visiting positions at the Isaac Newton Institute (1998 and 2005), the Université Paris-Sud (2001), Harvard (2007), and MIT (2007).