Clarence Douglas Ussher (September 9, 1870 – September 20, 1955) was an American physician and missionary in the Van region during the Armenian genocide, where he reported that 55,000 Armenians had been killed. In 1917 Ussher published a memoir regarding his experience in Van, titled An American Physician in Turkey: A Narrative of Adventures in Peace and War. It is considered one of the most detailed eyewitness accounts of the events. Ussher openly blamed the Turkish government for the systematic massacres of Armenians. His accounts of the Armenian genocide were depicted in the 2002 film Ararat. He was the husband of Elizabeth Barrows Ussher, who was also a witness of the genocide.