Mustafa Ahmed Adam al-Hawsawi (Arabic: مصطفى احمد ادم هوساوي; born August 5, 1968) is a Saudi Arabian citizen. He is alleged to have acted as a key financial facilitator for the September 11 attacks in the United States.

Mustafa al-Hawsawi was captured in Pakistan by Pakistani agents in March 2003 and was transferred to the custody of the United States. He was held in secret CIA black sites until September 2006, when he was transferred to Guantánamo Bay and U.S. officials finally acknowledged his imprisonment. It detained him at the Salt Pit, a secret black site in Afghanistan. It was reported in August 2010 that, after months of interrogation, the CIA transferred al-Hawsawi and three other high-value detainees to Guantanamo Bay detention camp on September 24, 2003, for indefinite detention. Fearing that Rasul v. Bush, a pending Supreme Court case about detainees' habeas corpus rights, might result in having to provide the men with access to counsel, the CIA took back custody on March 27, 2004, and transported the four men to one of their black sites.

It has long been known that, during al-Hawsawi's CIA captivity, his captors injured him, causing him to suffer from anal fissures, chronic hemorrhoids and, most seriously, symptomatic rectal prolapse. When the United States Senate Intelligence Committee published a 600-page unclassified summary of its 6,000-page report on the CIA's use of torture, the world learned that the CIA routinely punished its captives by sodomizing them, claiming the sodomy was the long abandoned medical technique of rectal feeding. The United States Senate Intelligence Committee's investigation of the CIA's Torture Program revealed that detainees were routinely subjected to unnecessary rectal exams without evidence of medical necessity for purposes of behavioral control. CIA leadership, including General Counsel Scott Muller and DDO James Pavitt, were alerted to allegations that rectal exams were conducted with "excessive force" on two detainees at the Salt Pit detention site. CIA records indicate that one of the detainees, Mustafa al-Hawsawi, was later diagnosed with chronic hemorrhoids, an anal fissure, and symptomatic rectal prolapse.

Al-Hawsawi was transferred from CIA custody to military custody at Guantanamo on September 6, 2006. The Bush administration was then confident of passage of the Military Commissions Act of 2006, which restricted detainee use of habeas corpus, and prohibited them from using the federal court system (this provision was, however, ruled unconstitutional in Boumediene v. Bush (2008), and numerous habeas corpus petitions were refiled in the federal courts). Al-Hawsawi remains incarcerated at Guantanamo Bay.