Dato' Seri Onn bin Ja'afar, KBE (1895 – 19 January 1962) was a Malay politician and a Menteri Besar (Chief Minister) of Johore in Malaysia, then Malaya. He was the founder of United Malays National Organisation (UMNO) and was also responsible for the social economic welfare of the Malays by setting up the Rural Industrial Development Authority (RIDA). His son was Tun Hussein Onn, the third Prime Minister of Malaysia and his grandson is Hishammuddin Hussein, currently the Minister of Defence in the Malaysian Cabinet. His mother was a Circassian from Turkey.