Thunderbird
Thunderbird had a short-lived career as an X-Man, and his contribution to the team was minimal, to say the least. The main problem with this character is that he was incredibly reckless, ultimately leading to his demise…

On his second mission, Thunderbird decided to take down an escape jet on his own. His team urged him to hold off, but in a bold move, he made a dash for it, and the jet exploded, taking him down with it.