X-Men are part of animated shows from 1966 but there are only three major X-men animated shows:
X-Men (1992–1997) ( aka X-Men: The Animated Series): This one was the first successful launch of X-Men in an animated medium and ran for 5 seasons and 76 episodes. The show also had crossover episodes with Spider-Man (1994 TV series) and was quite successful ...
As dull as it sounds, I'm not entirely sure there's actually a mutant behind Principal Kelly... Although if there had been, it might have been Mr. Sinister.
First because Kelly's comicbook counterpart is a major anti-mutant character.
More reading on his marvel.com page, but while obviously 30+ years of existence will have seen the character switch sides ...
Well, there were some rumours why this show was cancelled. Some claims that it wasn't cancelled but ended. However, the show producer Boyd Kirkland thought of cancelling the show because there was a conflict between management and financing partner regarding the budget for the show.
From Knows Why article,
Although many have claimed that the reason for ...
Prof X just overloaded himself (as Storm warned him that it's too much even for him).
And as Prof X state later he fainted when he was inside Kelly mind and was (probably) not able to wipe up his memory fully.