12 Most Dangerous X-Men
10. Beast
Another member of the original roster of X-Men, Dr. Hank "Beast" McCoy is not only an ever-evolving hairy blue behemoth, he's one of the most intelligent minds in the Marvel universe. However, unlike his contemporary genius Mister Fantastic, the thing that makes Beast so dangerous is his unshakable (and often unwarranted) confidence.
Beast is surprisingly arrogant, and seems to believe he is always ahead of the pack even when he's actually a few steps behind. This unwavering ego has, on several occasions, put both himself and his teammates in a lot of danger.
After all, it's his own fault that he is an ever-evolving hairy blue behemoth: without proper testing, he self-administered what he believed to be a cure to his original, non-fuzzy-and-blue mutation. This had the undesired effect of mutating him further, turning him into the savage version of Cookie Monster we know today.
Beast does not learn from his mistakes, and is notorious for leaping before he looks. He almost destroyed the entire time-stream continuum when he independently decided it would be a good idea to steal the original X-Men from the past and transport them to the present.
Even more recently, Beast decided to perform a lobotomy on a person that he believed to be a secret bio-sentinel, a procedure that any good doctor would have huge moral objections to. In doing so, he actually ended up unlocking their bio-sentinel abilities, which has put the entire mutant race in mortal danger.
Arrogance and smarts truly are a dangerous combination.