Mohammed Mani Ahmad al-Qahtani is a Saudi citizen who was detained as an al-Qaeda operative for 20 years in the United States's Guantanamo Bay detention camps in Cuba. Qahtani allegedly tried to enter the United States to take part in the September 11 attacks as the 20th hijacker and was due to be onboard United Airlines Flight 93 along with the four other hijackers. He was refused entry due to suspicions that he was trying to illegally immigrate. He was later captured in Afghanistan in the Battle of Tora Bora in December 2001.

The Guantanamo Bay detention camp is a United States military prison within the Guantanamo Bay Naval Base, also referred to as Gitmo, on the coast of Guantánamo Bay in Cuba. As of April 2023, of the 779 people detained there since January 2002 when the military prison first opened after the September 11 attacks, 740 had been transferred elsewhere, 30 remained there, and nine had died while in custody.