Carl Haessler (1888–1972) was an American political activist, conscription resister, newspaper editor, and trade union organizer. He is best remembered as an imprisoned conscientious objector during World War I and as the longtime head of the Federated Press, a left wing news service which supplied content to radical and labor newspapers around the country.
Carl Haessler was born August 5, 1888 in Milwaukee, Wisconsin of ethnic German parents. His father was a building contractor and his mother was a teacher in the Milwaukee public school system. Carl attended public school in Milwaukee and went on to college at the University of Wisconsin in Madison, from which he graduated in 1911 with a bachelor's degree in Latin.
During his early years, Haessler raised money for his education by working summers as a farm hand.
From 1911 to 1914, Haessler attended Balliol College of Oxford University in England. There he became interested in the socialist movement and joined the Fabian socialists.
Upon his return to the United States in 1914, Haessler took a job teaching in the Philosophy Department of Illinois University at Urbana. He also continued work on his Ph.D., which he received upon completion of his dissertation, entitled "The Failure of Scottish Realism."