He was really exceptionally smart. MIT has a lot of really smart people, and Danny stood out even among that rarified environment. He liked working on the hardest problems, as opposed to the easier ones, because they would make more of a difference.
― Tom Leighton, about Lewin
Daniel Mark Lewin (Hebrew: דניאל "דני" מארק לוין; May 14, 1970 – September 11, 2001), was an American–Israeli mathematician and entrepreneur who co-founded internet company Akamai Technologies.
On September 11, 2001, Lewin was seated in business class on American Airlines Flight 11, near Mohamed Atta and Abdulaziz al-Omari. Having served in the Israeli special forces, Sayeret Matkal, he was able to understand them when they spoke in Arabic and learned that they intended to hijack the plane. He confronted one of the hijackers but was attacked and stabbed to death by another hijacker, Satam al-Suqami. Hours later, the hijackers crashed the plane into the World Trade Centre, in an event that became known as the September 11 attacks or 9/11. Had Lewin succeeded in stopping the hijacking, it's likely that hundreds of lives would have been saved.