Onslaught
Real name: Onslaught is an amalgamation of Charles Xavier and Erik Magnus Lensherr, better known as Magneto.
First appearance: That gets complicated; Prof X and Mags both first showed up in Uncanny X-Men 1, but Onslaught didn't rear its ugly, helmet-encased head until X-Men (volume 2, that is) 54, after months of fore-shadowing.
What's His Problem? Onslaught's creation was the result of an insanely bad editorial decision to splinter the Marvel Universe and actually farm parts of it out to another company. It therefore represents unmoderated corporate greed at its most flagrant. Technically, he/it consists of the worst of the personalities of Charles Xavier, leader of the X-Men, and Magneto, the X-men's oldest and most dangerous foe.
Abilities: Onslaught possesses the complete psionic capabilities of Xavier, the most powerful telepath on the planet. In addition, he/it has a considerable portion of Magneto's ability to manipulate the magnetic spectrum, and leeched off a chunk of Nate Grey's powers as well.
Most Overused Quote:"Special ONSLAUGHT Update Inside!" Printed on the cover of every furshlugging Marvel comic for the same little four-page insert! Sheesh, talk about over-kill...
Heroes He Kept Running Into: Actually, since Onslaught inherited the petty jealousies of its two host minds, the first person it went after was Xavier's step-brother Cain Marko, AKA Juggernaut, who had made Charles' life miserable before either of them ever gained abilities beyond the norm. It next tackled Jean Grey, in what was possibly a botched seduction (hey, this is the repressed side of Xavier, remember?) Soon after that, it confronted the X-Men. After wiping the floor with them but failing to destroy them, basically every hero based in New York, from Captain America to Spider-Man to the Fantastic Four, took their shot. Alas, nothing could prevent the horror that is Heroes Reborn...
People Who Think He's Not So Bad: For a time, Onslaught masqueraded as Franklin Richard's imaginary friend. Once the masquerade was over, a number of powerful baddies came under Onslaught's influence, including the Dark Beast and Holocaust.
Most Despicable Act: Ripping Captain America away from the best creative team he had in years and giving him up to Liefield. Oh, and shunting all the New York-based non-mutant superheroes (and some of the mutant ones; consistency is not something Onslaught is big on) off to a pocket universe.
Hey! Where Are the Purty Pictures?! You think I'm wasting my valuable baud width on this tripe? Feh. I'm already cross about having to do this; I'm not spending any time scanning images of Onslaught as well!
Editor's Note: I think flushing 30 years of story continuity for a cheesy marketing ploy represents a really, really moronic idea. Can you tell?