[3][4] In order to join the team, Cyclops walked out on his new wife Madelyne Pryor, an Alaskan pilot who bore a strange resemblance to Grey, and their infant son, Nathan Christopher.

The five original members set up a business advertised as mutant-hunters for hire, headquartered in the TriBeCa neighborhood of downtown New York City,[6] posing as "normal" (non-superpowered) humans to their clients.

Despondent, Angel attempts suicide by detonating his airliner mid-flight, but Apocalypse rescues him and transforms him into Death, one of his Four Horsemen, giving him metal wings and blue skin.

In the 1989 crossover Inferno, Madelyne Pryor is revealed to be a clone of Jean Grey created by the mutant geneticist Mister Sinister.

Manipulated by demons and tormented by Scott's rejection of her, Madelyne becomes the Goblin Queen and fights X-Factor before kills herself in a suicide attack on Jean.

In the last major storyline of the first X-Factor series, published in early 1991, Apocalypse kidnaps Nathan Summers, sensing that he would grow up to be a powerful mutant and possible threat.

[volume & issue needed] X-Factor, the X-Men, and several minor characters team up to fight the telepathic Shadow King in another crossover event, The Muir Island Saga.

The new X-Factor, debuting in issue #71, included: Forge, a former government weapons contractor whose mutant power is an instinctive ability to invent advanced technology, was later added to the group; first replacing Cooper as their liaison after she had been compromised by one of Magneto's Acolytes, and later as an active member.

In a 1995 story, Multiple Man apparently dies of the Legacy Virus, a deadly illness that attacks mutant genes, which is later revealed to have only killed one of his duplicates.

Wild Child mutates out of control, Mystique hunts down Sabretooth (who had kidnapped young Tyler Trevor Chase), and Forge breaks ties with X-Factor.

The initial staff consists of Madrox's best friend and special enforcer, Guido Carosella (Strong Guy), and former teammate Rahne Sinclair (Wolfsbane).

Following the events of the "House of M" storyline, Madrox's new-found wealth from winning a Who Wants to Be a Millionaire?-style game show allows him to recruit several of his former colleagues from the Paris branch of the now defunct X-Corporation.

[16] The second incarnation of X-Factor appears in X-Men: The Animated Series, consisting of Forge, Polaris, Multiple Man, Strong Guy, Quicksilver, Havok, and Wolfsbane.