Onslaught
Marvel Comics. A company-wide cross-over that had many of Marvel's heroes disappear for a year.
1 The Awakening (Uncanny X-Men 322 (excerpts), 334; X-Men 53-54,
Onslaught: X-Men, Wolverine 104; w Mark Waid, Scott Lobdel, Larry Hama;
a Andy Kubert, Adam Kubert, Val Semeiks, Joe Madureira).
2 To the Victor... (X-Man 18-19, X-Force 57-58; w Jeph Loeb, Terry
Kavanagh; a Anthony Castrillo, Steve Skroce).
3 Comrades in Arms (Uncanny X-Men 335, Avengers 401, Fantastic
Four 415, X-Men 55; w Mark Waid, Tom DeFalco; a Mike Deodato Jr, Carlos
Pacheco, Andy Kubert).
4 Eye of the Storm (Cable 34-35, Incredible Hulk 444-445; w Jeph
Loeb, Peter David; a Ian Churchill, Angel Medina).
5 The Front Line (X-Factor 125, Amazing Spider-Man 415, Spider-Man
72, Punisher 11, Green Goblin 12; w Howard Mackie, Tom DeFalco, John Ostrander;
a Jeff Matsuda, Mark Bagley, Joshua Hood, John Romita Jr, Tom Lyle).
6 Pyrrhic Victory (Avengers 402, Fantastic Four 416, X-Men 56,
Uncanny X-Men 336, Onslaught: Marvel Universe; w Mark Waid, Scott Lobdell,
Tom DeFalco; a Mike Deodato Jr, Carlos Pacheco, Adam Kubert, Joe Bennett).
Return of the Heroes (4-issue mini; w Peter David; a Salvador Larroca). [From Marvel Comics: How did all of the heroes presumed dead in the battle with Onslaught return to the Marvel Universe? It all starts when it is discovered that the Franklin Richards (the near-omnipotent son of Mr. Fantastic and the Invisible Woman) placed them in an alternate world to save their lives! Now the powerful Celestials have approached the scared little boy and have told him he must choose between destroying the world he created and the world he lives in! Starring Iron Man, Thor, Captain America, Spider-Man, the Hulk, the Fantastic Four and more, this massive saga bridged Heroes Reborn to Heroes Return and jump-started the modern Marvel Universe!] 
Onslaught Reborn (5-issue mini; w Jeph Loeb; a Rob Liefeld).
[From Marvel Comics: Marvel’s greatest heroes sacrificed themselves to save the world from the deadliest threat they had ever faced: Onslaught! The lives of the Fantastic Four and the Avengers were saved only when Franklin Richards created a parallel universe, where we found those heroes, reborn! But this world has long since merged back into our own, and the evil Onslaught -- forged from the most vile parts of Magneto’s and Professor X’s psyches -- has been presumed long dead. But now, he, himself, is reborn -- and he’s bringing fragments of the other universe with him! Join comics superstars Jeph Loeb and Rob Liefeld in this no-holds-barred, all-out action extravaganza -- celebrating the 10th anniversary of the event that changed Marvel history -- as Onslaught, the Marvel Universe and the Heroes Reborn Universe collide in this massive crossover!] 2/6/08
Volume 1 (Uncanny X-Men 334-335; X-Men 53-54; X-Force 57; Cable 34; Avengers 400-401, Onslaught: X-Men, X-Man 18, Incredible Hulk 444; w Mark Waid, Scott Lobdell, Terry Kavanagh, Jeph Loeb, Peter David; a Andy Kubert, Pasqual Ferry, Joe Madureira, Mike Wieringo, Mike Deodato Jr., Adam Kubert, Steve Skroce, Anthony Castrillo, Ian Churchill, Angel Medina).[From Marvel Comics: It begins here! The saga that literally re-made the Marvel Universe of the 1990s is collected in chronological order across four volumes! The psionic force of nature known only as Onslaught sprang forth from the fractured psyche of mutant mentor Charles Xavier and the genetic terrorist called Magneto. Powered by his progenitors' rage, Onslaught laid siege to humanity -- touching off a cataclysmic conflict destined to deprive a world of its most revered icons!] 