Onslaught was a 1996 Marvel Comics Crisis Crossover involving nearly every superhero comic book they published at the time. The X-Men, Avengers, the Fantastic Four and other heroes fight an incredibly powerful Omnicidal Maniac which results in the "deaths" of every hero involved (except the mutants, Spider-Man and a Banner-less Hulk). Outside of comics, the series is best known for providing the Final Boss for Marvel vs. Capcom: Clash of Super Heroes.
The X-Men suffer several attacks by minions of the seemingly omnipotent entity known only as "Onslaught", who appears to know them well. He is also the one behind the recent stealing of the Sentinel fleet from a government base. When Gambit and Jean Grey go undercover to learn more about an unrelated Government Conspiracy, they are exposed but get an unexpected help from Onslaught. Later he tries to bring Jean over his side by showing her the dark long-repressed thoughts of her mentor Charles Xavier. She refuses. Juggernaut, who was attacked by Onslaught as well, comes to the X-Mansion and asks Jean to look for its true identity inside his head. She does and finds out that Onslaught is none other than Professor X.
It turns out that when Xavier brainwashed Magneto several months before (to cause him to stop being a threat after he cruelly stripped the adamantium off Wolverine's bones), a part of the latter's psyche merged with his own mind. Under the stress of constant failures and new misfortunes the Professor became more and more frustrated, until he developed a split personality, which eventually took a life of its own and was able to manifest in the corporeal world. Onslaught nearly kills the X-Men before leaving to capture Franklin Richards and X-Man in order to suck out their powers and become a living god. That brings him into conflict with both the Avengers, who were approached by X-Man, and Franklin's family, the Fantastic Four. Despite that Onslaught successfully kidnaps both of his targets, encircles Manhattan with Sentinels and prepares to Take Over the World.
The heroes (and Doctor Doom) eventually manage to defeat him but in order to do that most of them have to enter his non-corporeal form, which the X-Men then have to destroy, making it look like they killed them. Professor X is imprisoned for Onslaught's crimes and the anti-mutant sentiments become stronger than ever.
(Unknown to anyone, the heroes survived as they were recreated by Franklin's powers in another world, with no memory of their previous lives, as seen in the sequel "Heroes Reborn".)
Tropes used in Onslaught:
- All There in the Manual: X-Men: The Road to Onslaught, a special comic that told the backstory of Onslaught in chronological order.
- Almost Dead Guy: One of the first hints to the story was the X-Men finding a barely-alive Juggernaut.
- Arc Welding: The opening of Onslaught: X-Men does this to the traitor tape that was a part of Bishop's backstory, revealing that Jean sent it after Onslaught attacked X-Men—and hence that the X-traitor was none other than Professor X himself, not that he was the first to die (while he didn't die, either, Jean believed it was Juggernaut). The story also had Onslaught use an element from the early comics (Professor Xavier having the hots for Jean) to try to lure Jean to his side. Additionally, Onslaught's existence is traced back to Xavier mindwiping Magneto in retaliation for ripping out Wolverine's Adamantium in Fatal Attractions.
- Are We Getting This?: Trish Tilby reports on the final battle as the X-Men are forced to attack the Avengers and Fantastic Four to stop Onslaught.
- Bittersweet Ending: Onslaught is destroyed, but the Fantastic Four and many Avengers are seemingly killed in the process. The public also thinks the X-Men are responsible, triggering severe anti-mutant hysteria and Xavier being taken into government custody. Franklin Richards is orphaned and taken in by Generation X.
- Borrowed Catchphrase: Reed Richards pulls this off when leading the Fantastic Four and an army of their allies into the fray;Reed Richards: In the words of my dearest friend, It's Clobbering Time.
Ben Grimm: Couldn't have said it better myself.
- Brought Down to Normal:
- Charles Xavier loses his powers until they're restored in the "Hunt for Xavier" arc a few years later.
- Also, until his Face–Heel Turn, Phil Urich retires from being a Goblin after his Green Goblin costume is damaged in a fight with one of the Sentinels Onslaught commandeered.
- The Cavalry: Just when it looks like the X-Men have been defeated, the Avengers, Fantastic Four, and a whole host of other heroes arrive to join the battle.The Watcher: And yet... through the haze of dust, Xavier sensed a coming... of hope, of courage, of marvels.
- Continuity Snarl:
- Thor sports his shirtless "World Engine" look for the majority of the crossover, but changes into a new black costume in the last issue of his solo series, which takes place just before the final battle with Onslaught. In the actual finale of the crossover, Onslaught: Marvel Universe, Thor is inexplicably back to his shirtless look.
- Same thing happened with The Falcon. He was sporting his armored costume at the time, but is shown wearing his classic 70's uniform during the final battle with no explanation.
- Uncanny X-Men, Vol 1. #335 sees Moira MacTaggert and Excalibur aware of the crisis and that some of the X-Men were coming for the Xavier Protocols. Excalibur #100 saw the titular team busy with other matters and Moira surprised by the X-Men's visit.
- Crazy-Prepared: Turns out Professor X has made specific plans and instructions on how to deal with any X-Man (including himself), should they ever go rogue.
- Crossover Finale: This story was used to launch the Heroes Reborn initiative, with the Avengers and Fantastic Four seemingly falling in battle only to be whisked away to a pocket dimension Franklin Richards created. Its events also saw the retirement of Phil Urich—just in time for Norman Osborn to be revealed as The Clone Saga's Big Bad.
- A Darker Me: What happens when the dark sides of Xavier and Magneto combine.
- Darkest Hour: Onslaught announces his intention to wipe out all of humanity and then crushes the X-Men in battle. Fortunately, the Avengers and Fantastic Four arrive during the lull in fighting.
- Demonic Possession / Grand Theft Me : How Onslaught took control of the Red Skull.
- Did You Just Punch Out Cthulhu?: The Hulk literally punched Onslaught so hard that he destroyed his physical form.
- Onslaught punched him back hard enough to knock Bruce Banner out of the Hulk.
- Enemy Mine:
- Doom sides with the heroes and helps them against Onslaught. When he tries to collect an energy sample for his own ends, though, Hawkeye and Iron Man take him down.
- Apocalypse does try to help against Onslaught, though Cable and the Invisible Woman stop him from trying to kill the latter's son.
- Enemy Within/Enemy Without: Xavier's evil side had already manifested in physical form once before in the X-Men vs Micronauts series.
- Even Evil Has Standards: Despite the fact his methods involve murdering a child, even Apocalypse is horrified by Onslaught's actions.
- Evil Tower of Ominousness: Onslaught created one in Central Park.
- Forgot I Could Fly: Magneto has limited telepathic powers of his own, it was likely because of this that the mindwipe backfired. He just rarely uses them these days.
- Foreshadowing: Early on, Ben Grimm's newspaper horoscope says that he and a bunch of his closest friends will soon be going on a long trip.
- A God Am I: Onslaught at one point actually calls himself a god.
- Heroic Sacrifice: The heroes. (Doom was dragged along involuntarily by Iron Man.)
- Hoist by Their Own Petard: The Sentinels were designed to protect humanity from mutants. Onslaught enjoyed the irony of reversing that intent.
- Humans Are the Real Monsters: The original motivation of Onslaught was to Kill All Humans for their oppressing of mutants. Then he saw the world X-Man came from and decided that mutants are bastards too.
- Literal Split Personality: Onslaught and Xavier partway into the story, as well as Hulk and Banner at the end.
- Living Memory: How Xavier became Onslaught: a part of Magneto's attached itself to Xavier when he mindwiped Magneto.
- Mecha-Mooks: Sentinels.
- Mental Fusion: Onslaught is mostly Xavier with some Magneto. AXIS adds a heap of Red Skull to the mix.
- Nice Job Breaking It, Hero!: Separating Xavier from Onslaught. Instead of destroying him, it freed Onslaught from any sense of Xavier's morality and influence.
- Not-So-Imaginary Friend: Franklin's "invisible friend" Charlie. Onslaught did this to ensure he could kidnap Franklin right out from under the FF.
- Off with His Head!: One memorable scene had the Ben Reilly Spider-Man defeat a Sentinel by (with great effort) ripping its head off.
- Omnicidal Maniac: See above.
- Once More, with Clarity!: As noted under "Arc Welding", we're shown the X-traitor tape in its entirety at the official start of the crossover.
- Plot Archaeology: As noted under "Arc Welding", this picked up the X-traitor tape subplot, revealing that despite Bishop thinking Professor X was the first to die, Xavier was ironically (and unknowingly) the traitor himself. Furthermore his origins are tied to Xavier's mindwipe of Magneto in Fatal Attractions.
- Red Skies Crossover: Wolverine # 103 was labeled as tie-in but had no connection whatsover.
- The titles displaying the Crossover's logo were generally separated into two types, with directly affected titles branded "Onslaught: Phase (1, 2, or 3, depending on the month)" while the more Red Sky types were billed as "Onslaught: Impact (1, 2, 3)". Most of the "Impact" issues featured the heroes (e.g. Spider-Man) facing Onslaught-controlled Sentinels. Interestingly enough, there was an issue of The Punisher that had criminals hiding out inside the remains of a destroyed Sentinel.
- When Onslaught invades Four Freedoms Plaza in search of Franklin Richards, the boy ( actually Lyja in disguise) is seen watching his "favorite video," which appears to be an episode of Mighty Morphin' Power Rangers.
- In the final issue of Fantastic Four, Sue is holding one of Franklin's cherished toys, which appears to be a Goku plushy.
- So Proud of You: According to the narration during the beginning of the final battle, Xavier "never was prouder of his students."
- Split-Personality Takeover: What happened to Xavier, as Onslaught had been growing in Charles since mindwiping Magneto in Fatal Attractions.
- Superpowered Evil Side: While Xavier is one of the world's most powerful telepaths, Onslaught also had telekinesis and magnetism. He grew even more powerful upon capturing Franklin Richards and Nate Grey.
- Teacher/Student Romance: An old element from the early X-Men comics, namely Professor Xavier having feelings for Jean Grey, was used by Onslaught to try to get Jean to join him.
- Trailers Always Spoil: The Heroes Reborn line was advertised on the covers of Onslaught issues.
- Untouchable Until Tagged: Onslaught was unstoppable until his helmet was cracked.
- Wham Episode: Many of Marvel's major heroes are thought dead (actually sent to a pocket world), all remaining heroes have to pick up the slack (opening the door for the Thunderbolts development), the X-Men are blamed for the whole mess, and Hulk is split from Banner.
- Wham Shot: The image of Charles Xavier being inside the Onslaught armor after ripping the Gem out of Juggernaut's armor.
- What Happened to the Mouse?: In an issue of Spider-Man, Peter Parker and Ben Reilly defeat a few Sentinels and run off at the end of the issue to help the other heroes fight Onslaught. They never show up in any of the battles with no explanation.
- A Wizard Did It: Though other mutant heroes couldn't enter Onslaught's field (they'd get possessed) the Avengers' Scarlet Witch was able to make an exception for herself with her powers.
- The Worf Effect: Early on Juggernaut got beaten up by Onslaught to establish him as a big threat. It was before writers made up their minds about just anything else of him. It becomes unintentional Fridge Brilliance after The Reveal of Onslaught's identity: If you become evil and all-powerful, one of your first targets would be the invincible-til-now man who has bullied and tried to kill you from childhood to the present day.
- Would Hurt a Child: Apocalypse's idea to end the crisis was to kill Franklin Richards. Needless to say both Cable and the Invisible Woman put an end to that plan.