Carl Theodor Zahle (19 January 1866 in Roskilde – 3 February 1946 in Copenhagen), was a Danish lawyer and politician who served as the prime minister of Denmark from 1909 to 1910 and again from 1913 to 1920.

In 1895, he was elected as a member of the lower chamber of the Danish parliament, the Folketing, for the Liberal Party (Venstrereformpartiet).

A campaigner for peace, in 1905 he co-founded the Social Liberal Party (Det Radikale Venstre) together with other (mostly pacifistic) disgruntled members of Venstrereformpartiet.

He was interested in politics already in high school and saw himself as a convinced democrat in opposition to the Estrup government.

In 1909 he was able to form a minority government but had to resign as prime minister the year later following an electoral defeat for his party.

Although Denmark was neutral the war meant a scarcity of goods and materials and regulation of the economy became necessary.

The government was accused of having been too friendly towards Germany during the war and the economic regulations limited the profits of business life.