Eugene Victor Debs (November 5, 1855 – October 20, 1926) was an American union leader, one of the founding members of the International Labor Union and the Industrial Workers of the World (IWW), as well as candidate for President of the United States as a member of the Social Democratic Party in 1900, and later as a member of the Socialist Party of America in 1904, 1908, 1912, and 1920. Through his presidential candidacies as well as his work with labor movements, Debs would eventually become one of the best-known Socialists in the United States.

In the early part of his political career, Debs was a member of the Democratic Party of the United States. It was during this time that he was elected as a member of the Indiana General Assembly, which signaled the beginning of his career as a politician. After working with several smaller unions including the Brotherhood of Locomotive Firemen, Debs was instrumental in the founding of the American Railway Union, the nation's first industrial union. As a member of the ARU, Debs was involved and later imprisoned for his part in the famed Pullman Strike, when workers struck the Pullman Palace Car Company over a pay cut. The effects of the strike resulted in President Grover Cleveland calling in members of the United States Army into Chicago, Illinois, which led to Debs' arrest and imprisonment.

Debs' political views turned to socialism after he read the works of Karl Marx. He grew to be one of the most influential Socialists, the reputation helping him to garner five nominations for president. During the latter part of his life, Debs was imprisoned once more after being arrested and convicted under the Espionage Act of 1917 during the First Red Scare for speaking against American involvement in World War I. He was later pardoned by President Warren G. Harding, and died not long after being admitted to a sanitarium.