Original team (1986–1991)

X-Factor launched in 1986 featuring a team composed of the five original X-Men that debuted in X-Men #1 (1963).

Original writer Bob Layton wanted X-Factor to be a reunion of the original X-Men, an event complicated by the extensive histories of the characters following the initiation of a new team of X-Men in 1975.^[1] With the monthly Defenders series already due to be cancelled, Marvel's editorial staff elected to have the other members of the group killed off in the final issue in order to free up Angel, Beast, and Iceman for X-Factor.^[2]

A more difficult task was the return of Cyclops and Jean Grey. In 1980, Jean Grey was killed during the seminal Dark Phoenix Saga, and since it was considered vital that the team have a female member, Layton opted to use fellow mutant Dazzler.^[3] Publicity material for the series began to appear at this time, with images of the team using a blank space or silhouette in place of the female member as a teaser mystery.^[1][3] However, writer Kurt Busiek had earlier thought of a way to add Jean Grey to the roster which somebody else suggested that became one of the most significant cases of retroactive continuity in comic book history: Jean Grey had never actually been the Phoenix. Instead, the Phoenix entity copied Grey's identity and form, keeping her safe in a cocoon-like structure beneath Jamaica Bay. Busiek related the idea to Roger Stern, who related it to John Byrne.^[4] Byrne wrote and illustrated Fantastic Four #286 (1985), incorporating Busiek's idea. Several panels of this comic were rewritten (by X-Men writer Chris Claremont) and redrawn (by initial X-Factor artist Jackson Guice) to depict the Phoenix entity as less malevolent than Byrne intended.^[1]

Cyclops leaving his new wife Madelyne Pryor and their infant son, along with the resurrection of Grey in general, were highly controversial with fans.^[5]

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.

Bob Layton and Jackson Guice wrote and illustrated, respectively, the first few issues of X-Factor. They soon turned over creative duties to Louise Simonson (writer) and Walt Simonson (artist). Despite their relationship as husband and wife, both the Simonsons have said they did not approach work with each other any differently than any other collaboration; in particular, though Walt occasionally contributed ideas, he did not co-plot the series with his wife.^[7] In X-Factor #6 (1986), Louise introduced Apocalypse, who would appear in multiple issues and become X-Factor's nemesis.

Louise Simonson placed the series in line with the darker tone of most of the X-Men franchise; after a year on X-Factor, she remarked that "in real life all of my friends should be happy, but in comic books all of my characters should be miserable."^[7] In X-Factor #10, the Marauders, a group of mutant mercenaries, severely injure Angel's wings, which are later amputated. When an interviewer commented on the brutality of this turn of events, Walt Simonson replied, "Hey, that's nothing compared to what happens to him eventually."^[7]

Wanting to do stories with more focus on X-Factor's teenage wards, Louise Simonson successfully petitioned editor Bob Harras for permission to do a miniseries featuring them.^[7] Following the miniseries, titled X-Terminators, the characters left X-Factor and were moved to New Mutants.

Government team (1991–1998)

Rather than end the series, Marvel hired writer Peter David and illustrator Larry Stroman to recreate X-Factor with new members who worked for the Pentagon.^[8]

The lineup was selected by the X-Factor editorial staff. Legion was to be a member as well, but was dropped because it was felt the character was not suited to be a team player. David was instead given the option to use Quicksilver, which he has said was a pleasant surprise.^[8]

Commenting on his approach to the series, David said that his priority was to tell stories which developed the individual characters of the team, remarking "I feel there's nothing unique to the book if you come up with a generic plot and just plug in these characters."^[8]

David left in 1993. The series continued under writer J. M. DeMatteis and artist Jan Duursema, but struggled to distinguish itself among other X-books.

Writer John Francis Moore and illustrator Jeff Matsuda introduced a new X-Factor line-up, consisting of Forge as the team's new leader, Polaris, Cooper, and several new recruits.

Afterward, writer Howard Mackie injected more political and espionage elements into the series, a trend that culminated in the team's secession from government sponsorship. The popularity of X-Factor continued to dwindle and Mystique and Sabretooth, two popular X-Men villains, failed to draw in more readers.

In 1997, Marvel attempted yet another revival. After various stories focusing on individual characters, a new team was gathered. However, this version of the team disbands in the same issue in which they debut.

Although Marvel planned to revive X-Factor as an ongoing title after Mutant X ended, this did not happen for another 4 years.

Volume 2 (2002 miniseries)

A four-issue X-Factor limited series was launched in 2002. This series focused heavily on the "mutants as a metaphor for minorities" aspects of the X-Men concept. The series was written by Jeff Jensen with artwork by Arthur Ranson.

Volume 3 (2005–2013)

X-Factor Investigations is taken from the government-sponsored group the three founders previously served on.

Peter David put a noir spin on the mutant series and dealt with Jamie Madrox as the central character. The new series spun off of the "House of M" and "Decimation" storylines and also "Madrox" mini-series opens with a suicide attempt by Rictor, who has lost his powers.

Writer Peter David's decision to explicitly establish male characters Shatterstar and Rictor entering a romantic relationship in X-Factor #45 (August 2009), confirming clues that had been established in X-Force years earlier,^[9] drew criticism from Shatterstar's co-creator, Rob Liefeld,^[10] though Editor-in-Chief Joe Quesada supported David's story.^[11] David would eventually be nominated for and win a 2011 GLAAD Media Award for Outstanding Comic Book for this second run on the title.^[12][13]

In December 2009, the series adopted a cumulative numbering with issue #200, with 149 issues of the first volume plus 50 issues of the third volume constituting the previous 199 issues.^[14] During the Regenesis relaunch, Polaris and Havok joined the team in X-Factor #230.

The series ended with issue #262 in September 2013.^[15]

All-New X-Factor (2014–2015)

The next incarnation of the series was All-New X-Factor, written by Peter David and illustrated by Carmine Di Giandomenico. This version was announced as a part of the All-New Marvel NOW! initiative at the New York Comic Con in October 2013, and debuted in January 2014.^[16][17][18]

Volume 4 (2020–2021)

X-Factor was relaunched in July 2020 as part of Dawn of X written by Leah Williams and drawn by David Baldeon.

Vol. 1 (1986–1998)

Oversized hardcovers

Trade paperbacks