Issue: #2
This encyclopedia covers just about every x-related character in some capacity up until the year 2003. Marvel Encyclopedia, Volume 2, covers the various X-characters.
Creators: Phil Noto, Ethan Van Sciver, Jim Lee, Bill Sienkiewicz, Chris Bachalo, Mike Allred, Bryan Hitch, Esad Ribic, Jim Cheung, Leinil Francis Yu, John Byrne, Alex Ross, Joe Madureira, J.G. Jones, Frank Quitely, Mike McKone, Phil Jimenez, David Finch, Adam Kubert, Igor Kordey
Characters: Magneto, Rogue, Scarlet Witch, Storm, Arcade, Cannonball, Sunspot, Wolverine, Kitty Pryde, Domino, Mr. Sinister, Angel, Apocalypse, Beast, Colossus, Corsair, Cyclops, Emma Frost, Havok, Iceman