First Appearance: Madrox #1
Leader: Multiple Man > Siryn > Multiple Man > Havok > Multiple Man > Polaris
Line-up: Darwin, Havok, Layla Miller, Longshot, M, Multiple Man, Pip the Troll, Polaris, Rictor, Shatterstar, Siryn, Strong Guy, Tier Sinclair and Wolfsbane.
X-Factor Investigations Associates: Quicksilver, Nicole, Val Cooper
Multiple Man (James Arthur Madrox)
First Appearance: Giant-Sized Fantastic Four #4
Powers: Absorbs kinetic energy on impact to produce physical and mental duplicates of himself and any matter caught in his replication field
Membership Stints: Formed X-Factor Investigations (as XXX Investigations) prior to Madrox #1. Left the team between X-Factor (3rd series) #39 and #40 and travelled to the future. Rejoined the team at the end of X-Factor (3rd series) #50 and remained until his death in X-Factor (1st series) #227, when he was stabbed by Bloodbath. He was brought back to life in #232 and stayed on the team until it disbanded in #256.
Strong Guy (Guido Carosella)
First Appearance: New Mutants (1st series) #29
Powers: Superhuman strength, endurance and durability derived from hyper-augmented muscle mass, able to absorb kinetic energy to further increase his strength temporarily before the energy must be expeled
Membership Stints: Joined X-Factor Investigations (as XXX Investigations) prior to Madrox #1. Remained on the team until he quit in X-Factor (1st series) #241.
Wolfsbane (Rahne Sinclair)
First Appearance: Marvel Graphic Novel #4
Powers: Lycanthropic shapeshifter able to fully or partially assume the aspects of a wolf, variably increasing her strength, speed, agility, endurance, reflexes, senses, and recuperative powers while growing fur, fangs, and claws
Membership Stints: Joined X-Factor Investigations (as XXX Investigations) in Madrox #1 and left in X-Factor (3rd series) #28 to join X-Force. Rejoined the team between X-Factor (1st series) #208 and #209 and left again in #242 to look after her son. Rejoined in #250 and remained until the team disbanded in #256.
Banshee (previously Siryn) (Theresa Maeve Rourke, aka Theresa Cassidy)
First Appearance: Spider-Woman (1st series) #37
Powers: "Sonic scream" allows her to produce a greater range of sonic frequencies from her vocal chords and mentally alter the wavelengths to cause a variety of effects including deafness, hallucinations, vertigo, unconsciousness and adoration in others, sonic force to strike targets, deflect projectiles, or propel her for flight, sonic manipulation to block sounds, draw sounds from a distance, or emit sonar pulses, or destabilize matter to shatter glass, crumble masonry, etc.
Membership Stints: Joined the team between Madrox #5 and X-Factor (3rd series) #1 and left between X-Factor (3rd series) #50 and X-Factor (1st series) #200. She rejoined the team in #206 but departed in #244 when she became a god.
M (Monet Yvette Clarice Maria Therese St. Croix)
First Appearance: Generation X (1st series) #1 (as Penance), Generation X (1st series) #40 (as herself)
Powers: Superhuman strength, speed, endurance, reaction time, invulnerability, telepathic powers, and flight
Membership Stints: Joined the team between Madrox #5 and X-Factor (3rd series) #1 and left to help Banshee between #50 and X-Factor (1st series) #200. Rejoined in X-Factor (1st series) #200 and remained until she was killed in #255. She was resurrected after the team had disbanded.
Layla Madrox (née Miller)
First Appearance: House of M #4
Powers: Reanimation touch enables her to restore the dead to full health within a short time after their death, but they return without their souls; exists in a time-loop engineered by her future self with imprinted future memories temporally "hardened" by Doomlock technology, giving her absolute foreknowledge of her own lifetime
Membership Stints: Joined the team in X-Factor (3rd series) #1 and left in #25 when she travelled to the future. She rejoined the team in X-Factor (1st series) #206 and remained until the team disbanded in #256.
Rictor (Julio Esteban Richter)
First Appearance: X-Factor (1st series) #17
Powers: Decimated former mutant upon joining; later regained power to channel seismic energy as vibrational pulses from his hands or trigger earthquakes and geological activity on command
Membership Stints: Joined the team in X-Factor (3rd series) #3 and remained until he was sent into the Mojoverse in X-Factor (1st series) #256.
Longshot
First Appearance: Longshot #1
Powers: Enhanced strength, agility, reflexes, and leaping ability, supernatural sex appeal, psychometry allows him to read the history of and psychic imprints on physical objects, and a luck power which bends probability in his favor whenever he acted out of selfless motives; carries throwing knives that he can hurl with unbelievable accuracy thanks to his luck
Membership Stints: Joined the team in X-Factor (3rd series) #35 and remained until the team disbanded in X-Factor (1st series) #256.
Darwin (Armando Munoz)
First Appearance: X-Men: Deadly Genesis #2
Powers: Reactive self-evolution causes him to respond to his environment by adapting whatever attributes are necessary to protect him from harm or ill consequences, including spontaneously teleporting to safety if he cannot adapt fast enough; can also consciously evolve himself to achieve specific goals; adopted the aspect of the Death-Goddess Hela which increased the scope of his powers and gave him supernatural awareness
Membership Stints: Joined the team between X-Factor (3rd series) #38 and #39 and left in X-Factor (1st series) #213. Although he returned in X-Factor (1st series) #250, he never officially rejoined the team and only aligned himself with them due to circumstance.
Shatterstar (Gaveendra Seven)
First Appearance: New Mutants (1st series) #99
Powers: Enhanced strength, speed, agility, endurance, reflexes, senses, and regenerative powers, intuitive learning capacity for rapidly acquiring new skills, carries swords, knives, and retractable blades made of metal forged by science and magic, which channel his "force of will" as a vibratory shockwave conducted through the blades, or a teleportation effect slashing open a gateway with the blades, where a third-party he is emotionally anchored to must visualize the destination for his portals
Membership Stints: Joined the team between X-Factor (3rd series) #50 and X-Factor (1st series) #200 and remained until he was sent to the Mojoverse in #256.
Pip the Troll (Pip Gofern)
First Appearance: Strange Tales (1st series) #179
Powers: Empowered by the Space Gem as an intergalactic-ranged teleporter, able to teleport anywhere he has seen before or anywhere someone he makes contact with has seen before
Membership Stints: Joined the team in X-Factor (1st series) #213 and left between #249 and #250.
Havok (Alexander Summers)
First Appearance: X-Men (1st series) #54
Powers: Absorbs cosmic radiation and converts it into plasma wave discharges, causing sudden temperature shifts which make matter explode violently or disintegrate
Membership Stints: Joined the team in X-Factor (1st series) #229 and left in #245 to join the Unity Squad.
Polaris (Lorna Sally Dane)
First Appearance: X-Men (1st series) #49
Powers: Magnetic manipulation allows her to levitate and direct metal objects, cast magnetic force and solid barriers or bolts of energy, rearrange metallic structures, sense electromagnetic fields, absorb electrical energy, and fly through magnetic repulsion
Membership Stints: Joined the team in X-Factor (1st series) #229 and remained until the team disbanded in #256.
Tier Sinclair
First Appearance: X-Factor (1st series) #224
Powers: mutant wolf deity prophesized by the Death Gods, possessing superhuman strength, speed, agility, reflexes, durability and hyper-keen senses
Membership Stints: Joined the team in X-Factor (1st series) #250 and was killed by Strong Guy in #256.