Agent X

Agent X is an example of a character based on a character owned by the same company. Agent X was based on Deadpool with a similar sense of slapstick and cynical humor. Why would Marvel Comics do this? Brian Cronin (in his Comic Book Resources post "Comic Book Urban Legends Revealed #5!") theorized he was created in attempt to give more publicity to the creative team of Deadpool (whose comic had dipping sales at the time).
History
Nijo (his full name is unknown) was helping Black Swan attempt to kill Deadpool. However, Swan killed him for attempting to kill Sandi (Deadpool's assistant). However, Swan lost control of her powers and mixed the traits and abilities of Swan, Deadpool and Agent X. She accidentally resurrected Agent X and gave him a healing factor. Having lost his memories and gained a patchwork memory from Deadpool and Swan, Agent X became a mercenary and took the name "Alex Hayden". Swan took in Agent X and had Taskmaster and Outlaw trained Agent X. Swan and Alex formed the mercenary force Agency X. He went on various adventures. Deadpool confronted Agency X and attempted to restore the three (including Agent X) of them back to normal. Swan stole Agent X and Deadpool's powers. However, Agent X and Deadpool (aided by Outlaw, Taskmaster and several hired guns) managed to kill Swan. Agent X reformed Agency X and had them go on vacation. Agent X was later hired to stop Deadpool helping Cable, but failed.
Powers and Abilities
Agent X has regenerative healing. He is trained in weapons (especially related to marksmanship) and unarmed combat. His patchwork memory protects him from telepathy. He has above-average strength, decterity and speed.
Personality
Due to his fractured memory, he has attention deficit disorder. He has Deadpool's humor and the fine taste of Black Swan. He enjoys corn dogs (and related condiments) and shooting things.
References:
http://marvel.com/universe/Agent_X_(Nijo)
http://goodcomics.comicbookresources.com/2005/06/30/comic-book-urban-legends-revealed-5/
http://www.writeups.org/fiche.php?id=5106
http://en.wikipedia.org/wiki/Agent_X_(Marvel_Comics)