Mark Stephen DeJohn
- Bats Both, Throws Right
- Height 5' 11", Weight 170 lb.
- High School Middletown Woodrow Wilson High School
- Debut April 28, 1982
- Final Game June 29, 1982
- Born September 18, 1953 in Middletown, CT USA
DeJohn was a minor league instructor for the Tigers in 1983-1984, then in 1985 was briefly manager of the Birmingham Barons in the Tiger chain and was a coach for the Eugene Emeralds in the Kansas City Royals chain. He managed in the St. Louis Cardinals' chain from 1986 to 1991, followed by one year in the Tigers system. He returned to the Cardinals as minor league field coordinator (1993-1995) and big league coach (1996-2001). DeJohn managed again from 2002 to 2008. By 2011 he had returned to the position of Field Director.