Moe is a unique evolved centaur found in an area near Black Mountain that is unmarked in the map. He can mostly be found in the area's crater, in which two Brotherhood of Steelpaladins' corpses (Fairbanks and Hughes) can also be found. Moe is mentioned by Tabitha, Black Mountain's ruler, in her radio broadcasts as her favorite centaur.
Moe will usually be encountered during the quest Still in the Dark, in which the task is to find the dead Brotherhood paladins found in the crater in which he resides.
If killed, Moe will respawn, usually taking three in-game days.
Could be a possible reference to "Moe Szyslak" from the popular animated sitcom "The Simpsons", since a recurring gag used in the show is that Moe is hideous and repulsive, such as the appearance of the centaur.