John M. Jackson: John M. Jackson. Actor: A Few Good Men. John Murice Jackson (born June 1, 1950) is an American actor, best known for playing Rear Admiral A. J. Chegwidden on the CBS series JAG and also as a special guest star on its spin-off NCIS and recurring cast to its spin-off NCIS: Los Angeles.John was forced to use his middle initial "M." for his professional name because there was already a...
