Dato' Sir Onn bin Dato' Jaafar was a Malayan politician who served as the 7th Menteri Besar of Johor from 1947 to 1950, then Malaya. His organised opposition towards the creation of the Malayan Union led him to form the United Malays National Organisation (UMNO) in 1946; he was UMNO's founder and its first President until his resignation in 1951. He was famously known as the pioneer of organised anti-imperialism and early Malay nationalism within the entire Malaya, which eventually culminated with the Malayan independence from Britain. He was also responsible for the social and economic welfare of the Malays by setting up the Rural Industrial Development Authority (RIDA).

The Menteri Besar of Johor or Chief Minister of Johor is the head of government in the Malaysian state of Johor. According to convention, the Menteri Besar is the leader of the majority party or largest coalition party of the Johor State Legislative Assembly.