Martin Dies, Jr. (November 5, 1900 - November 14, 1972) was a Texas politician.

Dies was born in Colorado City, Texas. Dies was elected to Texas's 2nd District in the House of Representatives in 1930. Originally, Dies supported the New Deal, but he turned against it by 1937. Dies was the first chairman of the House Un-American Activities Committee. Dies was an unsuccessful candidate for the United States Senate in 1941. Dies was a critic of the Congress of Industrial Organizations. Dies retired from the House in 1944 after the CIO began a voter registration drive in his district and found a candidate to oppose him. Dies supported the Texas Regulars in the 1944 presidential election.

Dies returned to the House in 1952 in an at-large district. Dies ran for the Senate again in 1957, finishing second to Ralph Yarborough. Dies retired again from the House in 1958.