John M. Jackson

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 spinoff ''NCIS'' and recurring cast to its spinoff ''NCIS: Los Angeles''.

John was forced to use his middle initial "M." for his professional name because there was already a "John Jackson" registered with the Screen Actors Guild when he joined the union and SAG rules prohibit two or more members from using exactly the same name. Provided by Wikipedia