6 ft. tall 120 lbs. Dressed in a monk robe over what looks to be a suit in the school colors. Green catlike eyes that are somehow compulsive and commanding at same time. No hair. Otherwise appears non-descript and almost never has to raise his voice.
Anyone who has spent any amount of time in the libray has run afoul of Mr. Morgan. He believes that he is here to guard the books first. Just because they would best be protected if the students didn't feel the need to touch them, or read them, or even look at them, does nothing to subtract from his general air of authority.
Spoiler:
Morgan the Librarian is actually the human looking disguise that Morssgan Axveilismart wears to deal with the staff and students of Avalon Academy. Most never guess the truth because he augments his disguise with his disguise self spell-like ability, but the Headmaster and most of the other Alumni that have been around a while do know.