Codename: The Beast
Henry "Hank" McCoy is a founding member of the X-Men. Among all his original teamates, Hank had the best childhood, between loving parents, and so his temper and way of living was one of the happiest at the mansion. Beast's mutation at first was hardly noticable, but while away from the team, Hank made a terrible mistake: testing a new substance that he was using to study the x-factor. Beast tried the substance on himself. This caused a further mutation on his body, covering him with gray fur (that later became blue), fangs and great nails. He had then indeed become a "beast".
One of the only students at the mansion who took up an education beyond that of the Xavier school, Beast's studies were in the biogenetic area of his field. Possessing a quick wit, a wry sense of humour, and scholarly wisdom, he also has a pechant for quoting the classics and poetry.