Comic book characters who die are rarely gone for good. In worlds where magic and cosmic powers are commonplace, it's all too easy for characters to be resurrected, then be revealed to have not died in the first place or simply have their deaths retconned entirely.
It's no different in comic book movies and television shows – look at Nick Fury (Captain America: The Winter Soldier), Thor (Thor) and Phil Coulson (The Avengers) for proof of that – and just because someone seems to have perished doesn't mean we won't see them again.
Several villains have appeared to lose their lives in the Marvel Cinematic Universe (whether it's the audience who believe them to be dead or the other characters), but several of those presumed-dead characters will return. Here are the five most likely candidates in that regard.
Note that by "presumed-dead" we mean in-universe. We know audiences don't think that all of these characters are dead, but the other characters in the MCU certainly do.
Ronan was destroyed at the hands of the Guardians of the Galaxy, with Star-Lord, Gamora, Drax and Rocket Raccoon using the power of the Orb Infinity Stone to blast Lee Pace's character to bits.
However, Infinity Stones are very strange items and there's a good chance that Ronan may well have had his life-force absorbed into it – and of course that could be released at a later date, bringing him back to life in the process.
Moreover, prior to his demise, Ronan had promised Thanos that he was coming for him and that's not something the Mad Titan will simply let lie – even in the event of Ronan's death.
When Thanos has all of the stones in his possession and is wielding the completed Infinity Gauntlet, he may well bring Ronan back to life for the simple satisfaction of getting to kill him again.