Avengers 4: 6 Dead Characters Who Will Definitely Appear
2. Crossbones
His Death: Captain America: Civil War. Right at the start of the film, Crossbones detonates a bomb with the intent of killing himself - and taking Cap with him. Fortunately, Scarlet Witch traps the villain inside a bubble of energy before the explosion can do any harm, scorching him alive.
His Avengers 4 Role: Just this month, actor Frank Grillo - who appeared in The Winter Soldier as Rumlow, before being transformed into Crossbones in Civil War - confirmed he will appear in Avengers 4.
"He [Crossbones] makes an appearance in the next Avengers movie. But it's a flashback… I'm allowed to say whatever I want because I'm never doing another Marvel movie."
While he did not elaborate further, Grillo's comments further support the idea that Avengers 4 will prominently feature past events. Crossbones is unlikely to have a major role in the film (don't be surprised if he's onscreen for less than a minute), but if we're revisiting the Battle Of New York, then who's to say we can't revisit Civil War's Crossbones fight, or another event in Cap's past?
It's important to point out that Grillo states his character will appear in a flashback. This could mean he hasn't shot any new scenes, and old footage will be used instead. But then again, if that is the case, he probably wouldn't be privy to that information... so who knows!
Another possibility is that the filmmakers didn't divulge the nature of Grillo's scenes to him. He might think he's appearing in a flashback because he was wearing an old costume, but in reality, it could be a time travel or BARF sequence.