The House Committee on Un-American Activities (HCUA), popularly dubbed the House Un-American Activities Committee (HUAC), was an investigative committee of the United States House of Representatives, created in 1938 to investigate alleged disloyalty and subversive activities on the part of private citizens, public employees, and those organizations suspected of having either fascist or communist ties. It became a standing (permanent) committee in 1945, and from 1969 onwards it was known as the House Committee on Internal Security. When the House abolished the committee in 1975, its functions were transferred to the House Judiciary Committee.

The committee's anti-communist investigations are often associated with McCarthyism, although Joseph McCarthy himself (as a U.S. Senator) had no direct involvement with the House committee. McCarthy was the chairman of the Government Operations Committee and its Permanent Subcommittee on Investigations of the U.S. Senate, not the House.