Muhammad III as-Sadiq GCB (Arabic: ??? ??? ???? ???? ?????? ???? ????) ('As-Sadiq' (Arabic: ???????) = 'the righteous') (Bardo 7 February 1813 – Bardo, 27 October 1882) was the Husainid Bey of Tunis from 1859 until his death.
Invested as Bey al-Mahalla (Heir Apparent) on 10 June 1855, he succeeded his brother Muhammad II ibn al-Husayn on 23 September 1859.
Named as divisional General in the Imperial Ottoman Army on 10 June 1855, he was promoted to the rank of Marshal on 10 December 1859.