If you regularly read comic books, then you know that death is rarely permanent in the Marvel and DC worlds. Important characters will often meet their demise, but they'll eventually be brought back, whether it's through magical resurrection, cloning, time travel, the options are endless. Within the Marvel Cinematic Universe, death isn't nearly as much of a revolving door, but many of this franchise's most prominent characters are still around and kicking. But Avengers: Infinity War, as well as Avengers 4 next year, will throw the biggest conflict yet at this universe's heroes, and rest assured, there will be casualties.
We're coming up on the end of an era in the MCU, and while the franchise will continue into Phase Four and beyond, nothing is going to be the same. Certain characters, like Spider-Man and Black Panther, will still be around when this new era begins, there are other characters who should be killed off before we venture into this uncharted territory, whether it's because they've been around long enough or their character arcs are completed. Let's begin with the man whose kept the MCU anchored all this time.
Robert Downey Jr. has been part of the MCU since it launched with Iron Man in 2008, and I'd argue that if it wasn't for his performance as Tony Stark, this franchise wouldn't be as popular as it is today. It's been a blast watching Tony evolve from self-absorbed weapons manufacturer to superhero focused on the greater good (even though he has been responsible for a number of threats that have emerged). But after a decade of putting on armor and saving the world, it's about time for Tony to make his exit. He's had plenty of time in the spotlight, and with Robert Downey Jr. seemingly looking to wind down his time in the MCU and there being no plans to recast the character, Tony should finally depart. While it would be great if Tony could finally settle down with Pepper and live the rest of his years quietly and without drama, I also suspect that him going out in a blaze of glory in one final mission as Iron Man would be a good way for us to bid farewell to him.
Steve Rogers is a hero, there's no getting around that. Whether he's serving his country as Captain America or fighting the forces of evil without donning the red, white and blue uniform, his primary duty is protecting the innocent. So although part of me would be happy to see Steve somehow reunited with Peggy Carter, I also believe that ultimately him sacrificing his life to keep others safe, just like he thought he was doing at the end of Captain America: The First Avenger, is the best way for him to leave the MCU. Chris Evans has strongly implied that Avengers 4 will be his last Marvel movie, so unless Steve plans on retiring once the universe is safe, it's a good bet that he'll die on the battlefield. Fortunately, like in the comics, the Captain America mantle can be passed on to someone else (I vote Bucky Barnes).