With the recent releases in the Lego Marvel Superheroes theme, the official Lego X-Men Minifigures are slowly expanding. It seems to be an incredibly slow rate. The only reason we got the Scarlet Witch and Quicksilver is because of their appearance in the Avengers. There are so many iconic mutants in the Marvel Universe that most of them will probably never see an official figure. That leaves a great opportunity for custom Minifigs to fill in the roster.
Check out these Uncanny X-Men Minifigures created by agoodfella minifigs. This is the 2nd version of this collection, with new characters, updated appearances, and custom creations adding to the lineup. These feature custom paint, chrome, and even unofficial Minifigs. It all combines to create a roster of X-Men that look amazing.
There are a lot of mutants here. See if you can find Psylocke, Phoenix, Angel, Dark Phoenix, Sunspot, Warpath, Cable, Havok, Sabretooth, Archangel, Gambit, Bishop, X-23, White Queen, Magneto, Juggernaut, Deadpool, Iceman, Beast, Nightcrawler, Jean Grey, Wolverine, Colossus, Shadowcat, Rogue, Mystique, Cyclops, Professor X, and Storm.
The X-MEN v.2 [GROUP] is the creation of agoodfella minifigs, and can be found over on Flickr: https://www.flickr.com/photos/agoodfella77/16114389153/
Also check out the Lego X-Men & The Brotherhood Of Mutants Lego Minifigs over here: http://legogenre.com/lego-x-men-the-brotherhood-of-mutants/