John F. Seymour (born December 3, 1937) is an American real estate investor and politician.

Seymour served in the United States Marine Corps from 1955-1959 and graduated from the University of California, Los Angeles in 1962. Seymour was the President of the California Association of Realtors from 1978-1982.

Politically, Seymour, a Republican, served as a member of the City Council of Anaheim, California from 1974-1978, as Mayor of Anaheim from 1978-1982, a State Senator from 1982-1991, and United States Senator from California from 1991-1992. Seymour had been appointed to the U.S. Senate by Governor Pete Wilson, to serve in the seat Wilson had vacated to become Governor. Seymour's appointment was scheduled to last until the 1992 special election to select a replacement who would serve until the normal expiration of Wilson's term in 1994. Democrat Dianne Feinstein won the special election and was reelected in 1994 and 2000 Senate elections.