Abu Zubaydah ( (listen) AH-boo zuu-BAY-də; Arabic: ابو زبيدة, Abū Zubaydah; born March 12, 1971, as Zayn al-Abidin Muhammad Husayn) is a Saudi Arabian currently held by the U.S. in the Guantanamo Bay detention camp in Cuba. He is held under the authority of Authorization for Use of Military Force Against Terrorists.

Zubaydah was captured in Pakistan in March 2002 and has been in United States custody ever since, including four-and-a-half years in the secret prison network of the Central Intelligence Agency (CIA). He was transferred among prisons in various countries including a year in Poland, as part of a United States' extraordinary rendition program. During his time in CIA custody, Zubaydah was extensively interrogated; he was waterboarded 83 times and subjected to numerous other torture techniques including forced nudity, sleep deprivation, confinement in small dark boxes, deprivation of solid food, stress positions, and physical assaults. Videotapes of some of Zubaydah's interrogations are amongst those destroyed by the CIA in 2005.

Zubaydah and ten other "high-value detainees" were transferred to Guantanamo in September 2006. He and other former CIA detainees are held in Camp 7, where conditions are the most isolating. At his Combatant Status Review Tribunal in 2007, Zubaydah said he was told that the CIA realized he was not significant.

On July 24, 2014, the European Court of Human Rights ordered the Polish government to pay Zubaydah damages. Zubaydah said through his US lawyer that he would be donating the awarded funds to victims of torture.