Karl Gustaf Westman (18 August 1876 – 24 January 1944) was a Swedish historian and political leader.

Westman attended Uppsala University, where he earned a bachelor's degree in 1897, Licentiate of Philosophy in 1904 and a Ph.D. 1905.

In political office, he represented the Agrarian Bondeförbundet, which was established in 1913.

As a justice minister, and as one of the cabinet members with a say in matters of foreign policy during World War II, Westman has been criticized for what some observers have perceived as exaggerated adaptation to Nazi Germany's expected victory in the war, and for a limited respect for the freedom of the press to criticize foreign powers.

Westman was buried on 2 February 1944 at Gamla kyrkogården in Uppsala.