For many years, the X-Men had the backstory that the original team, minus Beast as he was with the Avengers at the time, went on a mission to the mysterious island of Krakoa and disappeared. Cyclops escaped and he and Professor Xavier put together a new team of mutants who went back to Krakoa and rescued the captured X-Men, making a new team that would go on to become Marvel’s biggest book.
More recently, a retcon came in. There had been for years talk of a third Summers brother after Cyclops and Havoc, and finally, that story was coming out. The third went by the codename of Vulcan, and he was part of a brief X-team that attempted a rescue of the original X-Men from Krakoa. That team appeared to die, and the distraught Cyclops was so upset that Professor X wiped his memory of this second X-Men team before sending out the familiar team that included Colossus, Wolverine, Storm, and Nightcrawler. Vulcan had managed to survive and came back much later very powerful and evil, but how?
Most big comics crossovers and story lines generally promise a death. Most of the time, the death is someone nobody really cares about. The death could be someone who rejoined the group after a sufficiently long absence, or some minor character, or someone no one really got around to liking anyway. Sometimes readers can even eliminate a few contenders by looking to see which characters have solo books that aren’t being canceled anytime soon. And sometimes the death is something even readers know won’t last very long, since the story itself seems to have set up a return somewhere along the line.
Then, occasionally, there’s a death that seems to come out of nowhere to a character people largely love, and in a way that just seems really cheap, with no clear path to return the character to the land of the living. One such death would be when Colossus was killed off in the pages of Uncanny X-Men.