Carl Theodor Zahle (19 January 1866 in Roskilde – 3 February 1946 in Copenhagen), Danish lawyer and politician; prime minister of Denmark 1909-1910, 1913-1920.
In 1895 he was elected member of the lower chamber of the Danish parliament, (Folketinget), 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 continued on as a member of the Folketinget for Det Radikale Venstre until 1928, when he became a member of the upper chamber of parliament (Landsting).
In 1929 he became Justice Minister, a post which he held until 1935.
.Zahle was instrumental in starting negotiations for a new Danish–Icelandic Act of Union (Dansk-Islandsk Forbundslov) in 1917, which resulted in Iceland being recognized as a sovereign nation in a personal union with the king of Denmark the following year.