Sayyid Hasan ar-Rida al-Mahdi as-Senussi (August 1928 – 28 April 1992) was the Crown Prince of the Kingdom of Libya from 26 October 1956 to 1 September 1969, when the Libyan coup d'état resulted in the monarchy being abolished.

Hasan was born in 1928 the fifth son of Muhammad ar-Ride as-Senussi (1890–1955, the brother of the then emir of Cyrenaica, Idris of Libya) and his tenth wife Imbaraika al-Fallatiyya.

As Crown Prince, he repeatedly undertook official trips abroad, notably to negotiate the purchase of U.S.-built jet fighters from the Kennedy Administration for the Libyan Air Force.

Following the revolution, Hasan was kept under house arrest in Libya, tried in the Libyan People's Court and sentenced to three years in prison in November 1971.

Prior to his death in 1992, he appointed his second son, Mohammed El Senussi (born 1962), to succeed him as head of the Royal House of Libya.