Sir Patrick Duncan, GCMG, KStJ, PC, KC (21 December 1870 – 17 July 1943) was the sixth Governor-General of the Union of South Africa, holding office from 1937 until his death in 1943.

Born in Scotland in 1870, he took degrees in classics at the University of Edinburgh and at Balliol College, Oxford, and studied law in the Inner Temple, before joining the British civil service in 1894 as a Clerk of the Upper Division in the Secretaries' Office for Inland Revenue.

[2] Although widely respected and above party politics, he made himself controversial in 1939 by refusing to call a general election on the question of whether or not the Union should enter World War II.

Hertzog, a former Boer General, wanted to stay neutral, but Parliament, included most members of his own party, supported his deputy, Jan Smuts.

Sir Patrick's refusal to call a new election rendered Hertzog a lame duck, after losing a vote of no-confidence he resigned from office.