The Popular Front for the Liberation of Palestine (PFLP; Arabic: الجبهة الشعبية لتحرير فلسطين, romanized: al-Jabha ash-Shaʿbiyya li-Taḥrīr Filasṭīn) is a secular Palestinian Marxist–Leninist organization founded in 1967 by George Habash. It has consistently been the second-largest of the groups forming the Palestine Liberation Organization (PLO), the largest being Fatah.

The PFLP has generally taken a hard line on Palestinian national aspirations, opposing the more moderate stance of Fatah. It does not recognize Israel and promotes a one-state solution to the Israeli–Palestinian conflict. The military wing of the PFLP is called the Abu Ali Mustafa Brigades.

The PFLP pioneered armed aircraft-hijackings in the late 1960s and early 1970s. More recently, the group has participated in the ongoing Gaza war alongside Hamas and other allied Palestinian factions. It has been designated a terrorist organization by the United States, Japan, Canada and the European Union.

Ahmad Sa'adat, who was sentenced in 2006 to 30 years in an Israeli prison, has served as General Secretary of the PFLP since 2001. As of 2025^[update], the PFLP boycotts participation in the PLO Executive Committee and the Palestinian National Council.

The PFLP grew out of the Harakat al-Qawmiyyin al-Arab, or Arab Nationalist Movement (ANM), founded in 1953 by George Habash, a Palestinian Christian from Lydda. In 1948, 19-year-old Habash, a medical student, went to his home town of Lydda during the 1948 Arab–Israeli War to help his family. While he was there, the Israel Defense Forces attacked the city and forced most of its civilian population to leave in what became known as the Lydda Death March. They marched for three days without food or water until they reached the Arab armies' front lines, leading to the death of his sister. Habash finished his medical education in Lebanon at the American University in Beirut, graduating in 1951.

In an interview with US journalist John K. Cooley, Habash argued for viewing "the liberation of Palestine as something not to be isolated from events in the rest of the Arab world" and identified "the main reason for [Palestinians'] defeat" as triumph of "the scientific society of Israel" over "our own backwardness in the Arab world"; because of this, he "called for the total rebuilding of Arab society into a twentieth-century society" and a "scientific and technical renaissance in the Arab world". The ANM was founded in this nationalist spirit. "[We] held the 'Guevara view' of the 'revolutionary human being'", Habash told Cooley. "A new breed of man had to emerge, among the Arabs as everywhere else. This meant applying everything in human power to the realization of a cause."

The ANM formed underground branches in several Arab countries, including Libya, Saudi Arabia and Kuwait, then still under British rule. It adopted secularism and socialist economic ideas, and pushed for armed struggle.

From 1962 to 1965, more than 145 ANM members, including Haddad, were trained in the Egyptian army's commando school at Inshas. Egypt also supplied the ANM in Lebanon with small amounts of arms and explosives.