Marvel Cinematic Universe: 10 MIA Villains Who Need To Return
3. Justin Hammer
Last Seen: All Hail the King
After the events of 2010's Iron Man 2, which saw Justin Hammer being taken into custody for his role in Ivan Vanko's big scheme, Justin Hammer made one further MCU appearance in 2014's All Hail the King One-Shot, making a quick cameo in Seagate Prison.
Though the first season of Luke Cage name-dropped him a number of times thanks to the existence of the infamous Judas Bullets, the character himself has yet to be seen since the One-Shot, which is unfortunate, as Sam Rockwell - aside from being an excellent actor the MCU would be remiss not to utilize again - has made it clear more than once that he's eager and willing to step back into the role.
Not to mention, the character has a pretty heavy grudge against Tony and Pepper; even if Tony doesn't survive the events of Avengers: Endgame, him resurfacing to try and destroy Pepper's life would be an interesting development for her character going forward. Or, if a character like Zemo shows up to form a group akin to the Masters of Evil, Hammer would serve as a perfect recruit for the villainous menagerie, both with the motive and resources to help, and hopefully Rockwell gets his patience rewarded one day soon for another spin in the franchise.