Sadiq al-Mahdi (Arabic: الصادق المهدي‎) (also known as Sadiq Al Siddiq, born December 25, 1935) is a Sudanese political and religious figure who was Prime Minister of Sudan from 1966 to 1967 and again from 1986 to 1989. He is head of the National Umma Party and Imam of the Ansar, a sufi sect that pledges allegiance to Muhammad Ahmad, who claimed to be Islam's messianic saviour, or the Mahdi.