5 Marvel Comics Villains Who Are Currently MIA
2. Vulcan
The most sinister of the Summers brothers, Gabriel hasn't been seen since War of Kings where it was presumed he died in a battle against Black Bolt, leader of the Inhumans. He's unfathomably powerful, so him being unaccounted for is very worrying for the Marvel Universe as he's easily dispatched the X-Men before.
Its hard to believe he hasn't popped up somewhere in the known universe and its unclear what happened to him or a lot of cosmic villains following Secret Wars. If he does return, it's likely that he'll be a problem for the Shi'ar Empire, as he'll be wanting his throne back from Gladiator, who became Majestor after Vulcan was presumed dead.
With unresolved issues with the Shi'ar, the Inhumans and the X-men, he's bound to make a big noise when he makes his pressence known again. Until then, the universe can rest easy for now.