Leader of Islamic extremist group, al-Qaeda. Believed responsible for the Khobar Towers bombing in Saudi Arabia, 1996, that left 19 servicemen dead, the simultaneous bombings of the US Embassies in Kenya and Tanzania in 1998 with 245 dead, the suicide bombing of the USS Cole in Yemen, 2000 with 17 dead, and of course the suicide attacks on the World Trade Center and the Pentagon. 2001. This single greatest terrorist attack in world history with approximately 3000 dead. His whereabouts are unknown.