15 Comic Book Characters Who Should've Stayed Dead
13. At Least SOME Of Onslaught's Victims
Onslaught was a being made of pure thought, a combination of the worst impulses of Magneto and Charles Xavier, and quickly became one of the most dangerous entities the X-Men ever battled. After seizing the powers of Franklin Richards (son of Mr. Fantastic and Invisible Woman) and Nate Gray (X-Man) for his own, he isolated the island of Manhattan with reprogrammed Sentinels.
It took the combined might of the X-Men, the Fantastic Four, and the Avengers to defeat Onslaught, but at a terrible cost, as Thor and every non-mutant member of the Fantastic Four and the Avengers (as well as Scarlet Witch) perished to put an end to the seemingly unstoppable foe.
But then it turned out they were all fine and living an alternate life inside Franklin Richard's magic Pokeball that retconned a lot of them to make them hipper, and it all felt really stupid after a while.