Siaka Probyn Stevens (24 August 1905 – 29 May 1988) was the leader of Sierra Leone from 1967 to 1985, serving as Prime Minister from 1967 to 1971 and as President from 1971 to 1985.
Stevens' leadership was often characterised by patrimonial rule and self worship, consolidating power by means of corruption and exploitation.Stevens and his All People's Congress (APC) party won the closely contested 1967 Sierra Leone general elections over incumbent Prime Minister Sir Albert Margai of the Sierra Leone People's Party (SLPP).
In April 1971, Stevens made Sierra Leone a republic and became president a day after the constitution had been ratified by the Parliament of Sierra Leone.
He was the second President of the Republic after Christopher Okoro Cole, a judge, who was sworn in for a day after which he resigned, paving the way for Stevens.
Stevens served as Chairman of the Organisation of African Unity (OAU) from 1 July 1980 to 24 June 1981 and engineered the creation of the Mano River Union, a three-country economic federation of Sierra Leone, Liberia and Guinea.
Stevens retired from office at the end of his term on 28 November 1985.
After pressuring all other potential successors to step aside, he chose Major-General Joseph Saidu Momoh, the commander of the Sierra Leone Armed Forces, as his successor.