Aside from Samuel L. Jackson's Nick Fury, Robert Downey Jr.'s Iron Man has been in the most MCU films, clocking in 10 appearances. However, most of these come from non-Iron Man movies, as a solo Tony Stark film has not been released since 2013's Iron Man 3.
In a recent interview with Vanity Fair, Avengers: Endgame writers Christopher Markus and Stephen McFeely explained why a fourth Iron Man solo film would not have made sense.
"Whether you like all of the 24 movies or not, the capital that Marvel built up allowed them to do things like make a movie starring a raccoon and a tree, right? You would’ve already had Iron Man 4 if it was any other studio," McFeely said. "But they decided, No, we’re going to take chances on all these other things. To put a flag in the ground and say, We’re going to end something and take characters off the table, is, I think, kind of daring, but selfishly it was really great for us."
"It needs an end or it loses meaning," continued Markus. "The end is what cements the thing, to actually sew it together and bring it to a crescendo, and yeah, take people off the board, finish their arcs. If Tony made it out the other side, and Iron Man 4 was waiting there, you’d be like, [shakes head] One too many..."
Aside from the Iron Man trilogy, Robert Downey Jr.'s Iron Man has appareled in The Incredible Hulk, The Avengers, Avengers: Age of Ultron, Captain America: Civil War, Spider-Man: Homecoming, Avengers: Infinity War and Avengers: Endgame. He and Samuel L. Jackson's Nick Fury were tied at 10 until Spider-Man: Far From Home, which put the super spy at 11 appearances.
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. The film is now available on Digital HD, Blu-ray and 4K UHD.