Thomas Christmas Riggs, Jr. (October 17, 1873–January 16, 1945) was an American Democratic politician who was the Governor of Alaska Territory from 1918 to 1921. He was born in Ilchester, Maryland and died in Washington, DC.

Riggs was engineer of the Alaskan Boundary Survey, 1906-13; Governor of Alaska, 1918-21; and United States Commissioner of the IBC about 1936-45. He was educated at Princeton University. He was in the lumber business in Alaska 1897-1901 and was with the Boundary Survey from 1903-05 before becoming engineer in 1906. He was in charge of the Fairbanks Division of location and construction of government railroads in Alaska before becoming the Governor of Alaska.

In 1947, the American Geographical Society named the Riggs Glacier after him.