Eugene Dennis (1905-1961) was a Communist Party leader and labor organizer in the United States. He was the general secretary of the CPUSA from 1945 until 1957, and the national chairman from 1959-1961. Dennis was also a member of the Industrial Workers of the World. In 1949, he was sentenced under the Smith Act with 10 other Communist Party leaders for conspiring to overthrow the government. He spent over three years in prison for this conviction.