Fatah al-Islam (Arabic: فتح الإسلام, meaning: Conquest of Islam) is a radical Sunni Islamist group that formed in November 2006 in a Palestinian refugee camp, located in Lebanon. It has been described as a militant jihadist movement that draws inspiration from al-Qaeda. It became well known in 2007 after engaging in combat against the Lebanese Army in the Nahr al-Bared UNRWA Palestinian refugee camp. Following its defeat at Nahr el-Bared, the group relocated to the Ain al-Hilweh refugee camp near Sidon in 2008. As of 2014, after the death or capture of many members, most of the surviving members of Fatah al-Islam are thought to have joined other groups in Lebanon and Syria including the Free Syrian Army, Al-Nusra Front, Ahrar al-Sham, and the Islamic State of Iraq and the Levant.

The United States Department of State classified the group as a terrorist organization on 9 August 2007 but it was not classified as such anymore on 24 November 2010.