John P. O'Neill, American FBI agent (b. 1952)
John Patrick O'Neill (February 6, 1952 – September 11, 2001) was an American counter-terrorism expert who worked as a special agent and eventually a Special Agent in Charge in the Federal Bureau of Investigation. In 1995, O'Neill began to intensely study the roots of the 1993 World Trade Center bombing after he assisted in the capture of Ramzi Yousef, who was the leader of that plot.

He subsequently learned of al-Qaeda and Osama bin Laden, and investigated the 1996 Khobar Towers bombing in Saudi Arabia and the 2000 USS Cole bombing in Yemen. Partly due to personal friction he had within the FBI and federal government, O'Neill left the Bureau in August 2001. He became the head of security at the World Trade Center, where he died at age 49 while helping to evacuate the North Tower during the September 11 attacks. O'Neill's life has been featured in a number of documentaries and books.