Sheikh Ahmed Ismail Hassan Yassin (1 January 1937 – 22 March 2004) (Arabic: الشيخ أحمد إسماعيل حسن ياسين ash-shaykh Aḥmad Ismāʻīl Ḥasan Yāsīn) was a Palestinian imam and politician. He was a founder of Hamas, an Islamist Palestinian paramilitary organization and political party. Yassin also served as the spiritual leader of the organization.

Yassin, a quadriplegic who was nearly blind, had used a wheelchair since a sporting accident at the age of 12. He was killed when an Israeli helicopter gunship fired a missile at him as he was being wheeled from early morning prayers in Gaza City. His killing, in an attack that claimed the lives of both his bodyguards and nine bystanders, was internationally condemned. Two hundred thousand Palestinians attended his funeral procession.