4. Len Wein
If youve never heard the name Len Wein before, I wont hold it against you. After all, the man has one of the shortest comic runs of any X-Men writer in history, a grand total of one issue. Wait, one issue? How is this guy worthy of note with only one issue to his credit? Its because that issue introduced a bunch of new characters to the X-Men. You may have heard of a few of themColossus, Storm, Nightcrawler, and some obscure character named Wolverine. While longtime veteran X-Men writer Chris Claremont deserves a great deal of credit for the development of these four characters, he did not create them, and Wein deserves full credit for his role in their conception. After Marvel turned the X-Men into a reprint title in the early 70s, they finally gave Wein and Cockrum a chance to completely revolutionize the book. Instead of focusing on American teenagers, this new incarnation of the X-Men would feature adult mutants hailing from all parts of the world, and they were almost all new characters: Storm (Kenyan), Nightcrawler (German), Colossus (Russian), Thunderbird (Apache), and Wein brought in a character he created as an antagonist in The Incredible Hulk, the Canadian Wolverine. Rounding out the team were reformed X-Men enemies Banshee (Irish) and Sunfire (Japanese). The concept of this issue, which was Giant-Size X-Men #1, was that the original X-Men investigated a powerful mutant presence on the island of Krakoa. Only Cyclops returned from this mission and Professor Xavier recruited these new X-Men to rescue their captive predecessors. This new team proved popular and with X-Men #95, Marvel began publishing new stories featuring them. Had Wein stayed on the title for more than one issue, perhaps he could have made it into the top five.