Sir Patrick Duncan, was the sixth Governor-General of the Union of South Africa, holding office from 1937 until his death in 1943.

The governor-general of the Union of South Africa was the highest state official in the Union of South Africa between 31 May 1910 and 31 May 1961. The Union of South Africa was founded as a self-governing Dominion of the British Empire in 1910 and the office of governor-general was established as the representative of the monarch. Fifty-one years later the country declared itself a republic and the historic link with the British monarchy was broken. The office of governor-general was abolished.