Gathered by the Timebroker, Weapon X was created to take on the missions and deal with the realities deemed too brutal for the Exiles. The team was originally made up of Weapon X Program inductees from different realities, hence their name. Unlike the Exiles, Weapon X was more than willing to fix each reality at any cost.
Originally led by Sabretooth, this team first encountered the Exiles during their mission to save Alpha Flight from being destroyed by a rampaging Hulk. They stayed out of sight and moved on without completing their assignment.
During later missions, they killed the Sub-Mariner and murdered a group of Morlocks as they slept. On their next trip, they teamed with the Exiles on a world where they were supposed to murder a childnamed David Richards. Weapon X attempted to complete the mission, but the Exiles stopped them. Sabretooth saved David by offering to stay behind in this reality and raise the mutant child to prevent him from becoming the evil dictator the Tallus had predicted for his future.
The team moved on with a new leader - Gambit. In a world controlled by Iron Man, the team, through trickery, were told to defeat the Inhumans but they were really there to set in motion a chain of events leading to the murder of Iron Man.
Weapon X met its most powerful member when the super-alien Hyperion joined the team. Hyperion decided the team should ignore the Tallus and choose a suitable reality and rule there as gods. The rest of the team, tired of being shunted from reality to reality and fearing the ruthless Hyperion, agreed. In the first reality they attempted to take over, the team was supposed to kill the last ten remaining mutants on the planet. Hyperion took those willing to serve under him and killed the rest. Unfortunately, Hyperion was unable to stop an Extinction Level Event-sized asteroid from destroying the Earth. He decided to complete the mission and the team moved on.
In a subsequent reality, Hyperion, tired of being tricked by Gambit, used his eye beams and blasted Gambit's Tallus arm off. Gambit lost his arm but the Tallus just switched wrists. Gambit escaped while Hyperion fought with Firestar and the Hulk, two members of Weapon X sent to force Hyperion's obedience. Hyperion then took over that reality's New York City.
Supposedly being driven insane by the conflicting personalities gathered on the two reality-hopping teams, the Timebroker sent the Exiles to the same reality. The Tallus informed the Exiles that in order to escape they would have to battle Weapon X to the death. The last six surviving members of both teams would move on and continue their reality-hopping ways. All of the members of Weapon X were destroyed, leaving the Exiles as the lone team serving the Timebroker.
Sabretooth - Former leader, active with Exiles
Gambit - Former leader, deceased (killed in explosion to destroy Hyperion)
Hyperion - Self-appointed leader, deceased (killed by Gambit)
Colossus - Deceased (blasted into space by Hyperion)
Deadpool - Deceased (neck snapped by Sabretooth)
Firestar - Deceased (disintefrated by own powers)
Hulk - Deceased (killed by Hyperion)
Iron Man - Deceased (armor malfunction)
Kane - Deceased (Killed by Sub-Mariner)
Ms. Marvel - Deceased (killed by falling building in battle with Morph)
Spider - Deceased (burned by Firestar)
Storm - Deceased (killed by soldiers while sent to kill Bruce Banner)
Vision - Deceased (destroyed by asteroid)
Hulk (Jen Walters) - Trapped in Negative Zone
Daredevil - Sent home
Angel - Sent home