Mark Jermaine Clayton (born July 2, 1982) is a former American football player. He played as a wide receiver for the St. Louis Rams of the National Football League. Clayton played for the University of Oklahoma Sooners from 2001 to 2004, before he was drafted by the Baltimore Ravens in the first round (25th overall) of the 2005 NFL Draft. Clayton's best season was in 2006 with Baltimore, when he had 67 catches, 939 receiving yards, and five touchdowns. Clayton struggled with injuries in his two seasons with St. Louis.