Ahmad Sa'adat (also transliterated from Arabic as Ahmed Sadat / Saadat; Arabic: احمد سعدات; born 1953), also known as Abu Ghassan, is a Palestinian militant and Secretary-General of the Popular Front for the Liberation of Palestine (PFLP), a Marxist–Leninist Palestinian nationalist organisation. Sa'adat graduated in 1975 from the UNRWA Teachers College, Ramallah, specializing in Mathematics. Sa'adat was elected General Secretary of the PFLP by its Central Committee in October 2001, to succeed Abu Ali Mustafa after his assassination by Israel during the Second Intifada.

Sa'adat had spent ten years in Israeli prisons, on eight separate occasions. He was accused by Israel of organizing the assassination of Israeli tourism minister Rehavam Ze'evi, and took refuge in the Muqata'a headquarters of PLO leader Yassir Arafat, which was then besieged by Israel after Arafat refused to hand him over to Israel. As part of an agreement with Israel, Sa'adat was tried by the Palestinian National Authority (PNA) and imprisoned at the Jericho prison in 2002. In the Palestinian elections of January 2006, Sa'adat was elected to the Palestinian Legislative Council. On 14 March 2006, Hamas announced their intention to release Sa'adat from prison. The US and British team monitoring Jericho prison left, citing poor security conditions. On the same day, Israeli forces carried out the so-called Operation Bringing Home the Goods, taking Sa'adat and five other security prisoners into custody. In December 2008 he was given a 30-year prison sentence by an Israeli military court. He was held in solitary confinement in an Israeli prison and his health deteriorated after frequent hunger strikes, in protest of Israel. Since 2012 Sa'adat is no longer in solitary confinement.