Origin
Not very much is known about Major Domo, except that he is the personal assistant of Mojo, a major producer of television programmes in his dimension, for many years now. He lives in the Mojoverse. He often aided his master, but always stayed out of any fights. He is known for being one of the few people whom can actually insult Mojo on a daily basis without being killed for it.
Creation
Major Domo was created by Ann Nocenti and first appeared in Longshot Vol.1 issue 4 (1985).
Major Story Arcs
Major Domo in Mojoworld
Major Domo has been a faithfull assistant to Mojo and has helped him come up with ideas on a number of ocsssions. One of his main advisories was Longshot, a former star-turned-rebel whom eventually fled the Mojoverse He and Mojo met the X-Men and numerous other mutants on a number of ocassions.
Major Domo was even the person that gave Mojo the idea of making his own X-Men, witch resulted in the creation of the X-Babies, mini versions of the X-men.
Major Domo’s name is most likely a joke to the word majordomo, which is a person who speaks, makes arrangements, or takes charge for another.
Other media
Television
X-Men Animated Series

Major Domo is seen in the X-men 1994 cartoon, in which the X-men are send off to Mojo World.