Carrie Coon, who played Avengers villain Proxima Midnight in Infinity War, would have reprised the role in Endgame. Unfortunately, due to a scheduling conflict, she was unable to return.
Proxima Midnight was one of the Children of Thanos and aided him in his quest to find the Infinity Stones. During the battle in Wakanda, the villain met her end at the hands of Scarlet Witch. However, despite Proxima's death, Coon confirmed on PeopleTV's Couch Surfing that the Russo Brothers asked her to return for Endgame, though she had to turn it down.
Proxima Midnight still makes an appearance in Endgame during the time-travel scenes, though she does not have any lines and she is not played by Coon. Rather, Coon's stand-in from Infinity War, Monique Ganderton, briefly took on the part.
Coon's Marvel journey started as nothing more than a mysterious voice-acting job, but the Russos were a big fan of her previous work on The Leftovers and Fargo, and the role expanded. "I got a voice-over audition; it was not specified what the project was," she explained. "They were being very secretive about it, but I was given some of the lines that did end up being in the film. [The Russos] were excited about the possibility of me actually physicalizing the character as well, and they invited me to come down to Atlanta." The then-pregnant Coon accepted and spent about 12 hours on set.
Coon hopes to return to the Marvel Cinematic Universe, though, saying, "It's very possible I could have my own Avengers movie next. But I wouldn't hold your breath."
After the devastating events of Avengers: Infinity War (2018), the universe is in ruins due to the efforts of the Mad Titan, Thanos. With the help of remaining allies, the Avengers must assemble once more in order to undo Thanos' actions and restore order to the universe once and for all, no matter what consequences may be in store.
Directed by Joe and Anthony Russo, Avengers: Endgame stars Robert Downey Jr. as Iron Man, Chris Evans as Captain America, Mark Ruffalo as Bruce Banner, Chris Hemsworth as Thor, Scarlett Johansson as Black Widow, Jeremy Renner as Hawkeye, Brie Larson as Captain Marvel, Paul Rudd as Ant-Man, Don Cheadle as War Machine, Karen Gillan as Nebula, Danai Gurira as Okoye and Bradley Cooper as Rocket, with Gwyneth Paltrow Pepper Potts, Jon Favreau as Happy Hogan, Benedict Wong as Wong, Tessa Thompson as Valkyrie and Josh Brolin as Thanos.
(via EW)