Ramzi bin al-Shibh

Ramzi Mohammed Abdullah bin al-Shibh (Arabic: رمزي محمد عبد الله بن الشيبة, romanized: Ramzī Muḥammad Abd Allāh bin al-Shībh; born 1 May 1972) is a Yemeni citizen currently being held by the U.S. as an enemy combatant detainee at Guantanamo Bay in Cuba. He is accused of being a "key facilitator for the September 11 attacks" in 2001 in the United States.

In the mid-1990s, bin al-Shibh moved as a student to Hamburg, Germany, where he allegedly became close friends with Mohamed Atta, Ziad Jarrah and Marwan al-Shehhi. Together, they are suspected of forming the Hamburg cell and becoming central perpetrators of the September 11 attacks. He was the only one of the four who failed to obtain a U.S. visa; he is accused of acting as an intermediary for the hijackers in the United States, by wiring money and passing on information from key al-Qaeda figures. After the attacks, bin al-Shibh was the first to be publicly identified by the U.S. as the "20th hijacker", for whom there have been several more possible candidates.

Bin al-Shibh has been in United States custody since he was captured on 11 September 2002, in Karachi, Pakistan. He was held by the CIA in black sites in Morocco before being transferred to Guantanamo Bay in September 2006. Finally charged in 2008 before a military commission, he and several others suspected in the 9/11 attacks went to trial beginning in May 2012. In August 2023 a U.S. military judge ruled him too psychologically damaged to defend himself after CIA torture.