8 X-Men Characters You Didn't Realise Had Died
8. Multiple Man
Jamie Madrox, aka the Multiple Man, really came into his own in Peter David's X-Factor. David's '90s series run and subsequent reboot in 2005 gave Madrox a lot of much needed character development. And that's why his death is so strange.
Without getting into too much context, at the aptly named Death of X storyline the Inhumans sent clouds they call Terrigen Mist around the world to awaken dormant Inhumans. The problem is the mist was found to be poisonous to mutants, creating an inevitable conflict between the two groups.
Jamie Madrox was killed by the Terrigen Mist in 2016 as setup for the conflict. That in itself isn't that strange. Plenty of important characters are killed as fodder for crossover storylines. What is strange is that Jamie was killed in a single page as exposition.
Madrox wasn't being used in any X-books at the time. The mixture of his rather unceremonious death and his infrequent usage caused a lot of people to miss his death entirely.