Carl Johan Gustaf Swartz (5 June 1858 – 6 November 1926) was a Swedish right-wing politician who served as Prime Minister of Sweden from March to October 1917.

With the amalgamation of the right-wing groups of the Riksdag's lower chamber, Swartz became a member of the inner council of the newly formed Nationella Partiet (English: The National Party) in 1912.

With the fall, due to external pressures and internal disharmony, of the government of non-party aligned Hjalmar Hammarskjöld, King Gustav V called on the party-political conservative Swartz to become prime minister.

The new government's foremost task was to exercise a calming influence on the bourgeois which was worried, in anticipation of 1 May 1917, by rumours that the February Revolution in Russia would spread to Sweden.

He forbade private bourgeois militias in advance of the 1 May 1917 demonstrations, in return for the Social Democratic Party's assurance that they would be responsible for maintaining order.

Swartz also quickly concluded negotiations with the Triple Entente powers, principally Great Britain, on imports from the west, which Hammarskjöld had prevented.