Clayton Anthony Fountain (September 12, 1955 – July 12, 2004) was an American federal prisoner, member of the Aryan Brotherhood, and murderer.

While his father served combat tours in Korea and Vietnam and his mother was working, Clayton, as the oldest child in family, became a surrogate for both parents when he was very young.

The incidents resulted in a 23-year lockdown at Marion, and contributed to the creation of the federal supermax prison, United States Penitentiary, Florence ADX.

Fountain converted to Catholicism, and completed several educational courses on theology during the twenty years he spent in virtual isolation.

He developed ties with an order of Trappist monks, and was accepted posthumously as a lay brother after his death from a heart attack in 2004.