The first X-Factor, launched in an eponymous series in 1986, features a team consisting of the five original X-Men, but the series also features several young “wards” of the team. In 1991, the founding members were incorporated back into the X-Men. However, X-Factor continued, focusing on a second X-Factor team, a U.S. government-sponsored team incorporating many secondary characters from the X-Men mythos. It was cancelled in 1998.
In 2006, a new X-Factor series was launched, following the mutant detective agency X-Factor Investigations.
The founding of X-Factor hinged upon the 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.
In the 1970s and early 1980s, Angel, Beast, and Iceman wandered through various superhero teams. By 1985, all three were members of the Defenders, whose monthly series was shortly canceled which freed the trio.
The returns of Cyclops and Jean Grey were more difficult. In the late 1970s, Grey had bonded with a cosmic entity called The Phoenix and Jean Grey/Phoenix died in the seminal Dark Phoenix Saga. A 2008 online reply by Bob Layton revealed that early X-Factor concepts actually accommodated Jean's death by leaving the female member of X-Factor undefined, with Dazzler as a strong candidate for the role However, future Marvel writer Kurt Busiek suggested a solution to this problem, which became one of the most notorious examples of retconning 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. Byrne wrote and illustrated Fantastic Four #286 (1985), in which Jean was discovered and the truth revealed.
In order to reunite the rest of the original X-Men, Cyclops walked out on his new wife Madelyne Pryor, an Alaskan pilot who bore a strange resemblance to Grey, and their son Nathan. Cyclops' uncharacteristic behavior and the resurrection of Grey were highly controversial with fans. Since being so 'out of character', it was later retconned in the 'Inferno' cross-over that Mr. Sinister was manipulating Cyclops to walk out on his wife so she could become the Goblyn Queen. Even though Jean Grey learned this secret, Cyclops did not, and his actions still haunt him to this day.
The team would also go into action in costume, posing as mutant outlaws known as the "X-Terminators." Eventually, the team decided that the "mutant-hunter" ruse did more harm than good by inflaming hatred. Not only was the concept rejected, but it was blamed on X-Factor's original business manager, Cameron Hodge, who was revealed as a mutant-hating mastermind.
Bob Layton and Jackson Guice wrote and illustrated, respectively, the first few issues of X-Factor. They soon turned over creative duties to married collaborators Louise Simonson (writer) and Walt Simonson (artist). Louise Simonson introduced in X-Factor #6 (1986) Apocalypse, who would go on and become X-Factor's arch-nemesis. The Simonsons placed the series in line with the darker tone of most X-Books. In X-Factor #10, the Marauders, a group of savage mutant mercenaries, severely injured Angel's wings and which were later amputated. Despondent, Angel attempted suicide by detonating his airliner mid-flight, but Apocalypse rescued him from the wreckage and transformed him into Death, one of his Four Horsemen. Death was a fearsome creature that possessed metal wings and blue skin. Angel escaped Apocalypse's control, but the physical changes to his body remained. He became known as Archangel and became a much darker character. Angel's replacement on X-Factor, Caliban, also later turned to Apocalypse for more power.
In the 1989 crossover Inferno, Madelyne Pryor was revealed to be a clone of Jean Grey created by the nefarious mutant geneticist Mister Sinister. Demons had used Madelyne's pain at Scott's rejection of her to manipulate her into becoming the Goblyn Queen. Madelyne planned to sacrifice Nathan to open an interdimensional portal and to hurt Cyclops and Sinister as much as possible. X-Factor teamed up with the X-Men to rescue Nathan, bridging the gap between the two teams. Madelyne suffered a mental breakdown upon discovering she was a clone and killed herself.
During Inferno, X-Factor's teenage wards, along with a young paraplegic mutant named Taki Matsuya, starred in the X-Terminators miniseries and shortly after folded into the X-Men's junior team, the the New Mutants.
In the last major storyline of the first X-Factor, published in early 1991, Apocalypse kidnapped Nathan Summers, sensing that he would grow up to be a powerful mutant and possible threat. X-Factor rescued Nathan from Apocalypse's lunar base, but found him infected with a "techno-organic" virus that could not be treated in the present time. A clan of rebels from the future, known as the Askani, sent a representative to the present time to bring Nathan 2,000 years into the future to be treated. Fully grown, he would return to the 20th Century as the anti-hero Cable.
Shortly after this, X-Factor, X-Men and several minor characters teamed-up to fight the telepathic Shadow King in another crossover event, The Muir Island Saga. Afterwards, the original members of X-Factor rejoined the X-Men and several minor characters from various X-Men-related series became founding members of the all-new X-Factor.
The era of the original X-Factor had lasting effects on the X-Men mythos. It introduced Apocalypse and the Archangel version of Angel and explained the connection between Apocalypse, Cable, Cyclops, Jean Grey, Pryor, and Sinister. All of these elements continued in future X-Men series.
Although X-Factor was not as flashy or wildly popular as other X-Books, David was applauded for his use of humor and cultural references and his ability to flesh out characters that had previously only been background characters.
David left in 1993. The series continued under writer J. M. DeMatteis and artist Jan Duursema, but struggled to distinguish itself among other of X-books. Shortly before David's tenure on the book ended, Forge, a former government weapons contractor whose mutant powers were his brilliant engineering skills, was 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. Cooper later became an active member as well, her marksmanship and athletic skills compensating for her lack of superhuman powers.
By 1995, Multiple Man had apparently died of the Legacy Virus, a deadly illness that attacked mutant genes, which was later revealed to have killed only one of his duplicates. Strong Guy was put into suspended animation after suffering a heart attack caused by the stress his extra mass put on his body. Wolfsbane, who had been cured of her fake love for Alex, transferred to the European mutant team Excalibur. Havok left to infiltrate a mutant terrorist ring.
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:
Afterwards, writer Howard Mackie injected more political and espionage elements into the series, a trend that culminated in the team's secession from government sponsorship. Multiple Man and Strong Guy appeared again at the same time. Despite Forge managing to fix Strong Guy's problems, he did not rejoin the team. The popularity of X-Factor continued to dwindle and Mystique and Sabretooth, two popular X-Men villains, failed to draw in more readers. Wild Child mutated out of control, Mystique hunted down Sabretooth (who had kidnapped young Tyler Trevor Chase) and Forge wanted nothing to do with X-Factor.
In 1997, Marvel attempted yet another revival. After various stories focusing on individual characters, a new team was gathered consisting of Havok, Multiple Man, Polaris, Shard and several other members of the X.S.E.; Archer, Fixx and Greystone; brought to the 20th Century. But this version of the team was disbanded the issue they debuted. In that issue, #149 (1998), Greystone built a time machine meant to take him and his compatriots back to the future. However, the device exploded, killing Greystone and apparently Havok. Afterwards, X-Factor disbanded.
In fact, the time machine transported Havok to a parallel world, populated by twisted versions of Marvel characters. He explored this strange world in the series Mutant X, which lasted from 1998 until 2001. Although Marvel planned to revive X-Factor after Mutant X ended, this never happened.
As of stories published in 2007, Multiple Man, Strong Guy, and Wolfsbane have formed a new X-Factor (see below), Havok and Polaris are members of the Starjammers, Mystique has joined the Marauders, Sabretooth and Shard have died, and Archer and Fixx were never seen again.
The initial staff consisted of Madrox's best friend and special enforcer, Guido Carosella (Strong Guy) and former teammate Rahne Sinclair (Wolfsbane). Following the House of M, Madrox newfound wealth from winning a Who Wants to Be a Millionaire?-style game show allowed him to recruit several of his former colleagues of the Paris branch of the now defunct X-Corporation. New members include M, a powerless Rictor, Siryn, and Layla Miller, who has inserted herself into the group to keep them from discovering the truth behind the mutant Decimation.
The members of the team, as constituted in early 2007: Guido, Jamie, Layla, Monet, Rahne, Rictor, and Siryn. An eighth member was acquired temporarily a little later in 2007, when Monet rescued (or abducted, depending on your viewpoint) a French orphan girl named Nicole (with the reluctant help of Siryn and the clandestine help of a mysterious hooded personage of great power) and took her back to America. Nicole was supposedly the orphaned daughter of ex-mutants lynched by a mob. Monet felt personally responsible for Nicole because she had tried, but failed, to prevent the pogrom. Nicole, in an attempt to kill Layla, is later revealed as a robot and hit by a train. Nicole's cover story was a total fabrication. She had been manufactured as a tool to destroy X-Factor.
Peter David has put a noir spin on the mutant series and has dealt with the former Multiple Man, Jamie Madrox as the central character. The new series spins directly out of House of M and opens with a suicide attempt by Rictor, who has lost his powers in the Decimation that has caused 90 percent of all mutants to lose their powers. The series deals with the attempt by the group to unravel the truth behind the decimation and its aftermath, getting involved with the events of Marvel's crossover Civil War, fighting with Singularity Investigations, and dealing with Madrox's powers and the consequences of it.
The team also attempted to protect Professor Xavier when the Hulk attacked him and the New X-Men.
In the first half of 2008, Jamie and Layla travel to a hideous future in which mutants are persecuted and imprisoned. Jamie manages to escape, and to return to the early 21st century, but Layla is still trapped in that undesirable future. Rahne believes she knows that Layla will return and will marry Jamie when she grows up. However, she fears (because of a glimpse she has had of the future) that she (Rahne), while in her wolf shape, will murder both Jamie and Layla. To prevent this, she quits the team and joins X-Force. Rictor also quits. The team is down to only four members: Jamie, Guido, Monet, and Siryn. They are attacked by a villain with a plan to kill all Mutants.