In comics, if writers want to have, say, Doctor Strange pop-up in a Spider-Man run for a couple of s, all they need to do is clear it with the higher-ups and get it drawn. In the movies, well, it's not so simple.The Marvel Cinematic Universe is a sprawling behemoth. The highest grossing movie franchise of all time, it's now fourteen films deep and has a good ten more in the pipeline (with Infinity War and its untitled sequel being shot back-to-back, likely the result of cast-wide contract discussions. With that established, let's break down the current MCU slate.Iron Man, Captain America, And Associated Heroes (This Page)

Robert Downey Jr - Tony Stark/Iron Man

Films left on contract: 3 (Spider-Man: Homecoming, Avengers: Infinity War, Avengers 4).

The first star of the MCU, Robert Downey, Jr. originally signed on for three Iron Man movies and The Avengers (his cameo in The Incredible Hulk is uncredited). His contract has been extended three times since - first to finally Spider-Man: Homecoming.

The prospect of an Iron Man 4 has been teased a lot over the years, but as we move further into Phase 3 and a changing makeup of the MCU, that looks less likely. For now, his last set appearance is in Avengers 4.

Don Cheadle - James Rhodes/War Machine

Films left on contract: Unknown

Don Cheadle's played James Rhodes four times since replacing Terrence Howard in Captain America: Civil War, though, meaning he will probably pop up in these films or later. The length of his contract is also a mystery, although seeing as he ed in the early days of the franchise it's likely no more than six (explaining the slowed appearances).

Iron Man's ing Characters

Based on her absence since 2013 and Iron Man 3 or she simply hasn't been asked back.

Jon Favreau's Happy Hogan looks to be in a similar situation, although as he is going to appear in Spider-Man: Homecoming, the chances of a further extension are a bit more likely.

Chris Evans - Steve Rogers/Captain America

Films left on contract: 3 (Spider-Man: Homecoming, Avengers: Infinity War, Avengers 4)

Marvel originally wanted Chris Evans on a nine-movie contract, but he negotiated them down to six: a trilogy of solo movies and three Avengers films. This deal no qualms about an extension. For now, though, Avengers 4 is his end.

Beyond his six movies, Evans has had a couple of cameos in Homecoming. The latter was uncredited, so didn't affect his total, while Homecoming likely required renegotiations - as it did with RDJ.

Sebastian Stan - Bucky Barnes/Winter Soldier

Films left on contract: 6 (Avengers: Infinity War, Avengers 4, others unknown)

Despite three major roles in each Captain America films, Sebastian Stan is nowhere near done with his massive Black Panther, instead returning to the fray in Avengers: Infinity War. Long-term, Bucky is expected to follow his comic counterpart and take up the Captain America mantle from Steve Rogers, meaning he could be the lead of an eventual Captain America 4 (and more).

Anthony Mackie - Sam Wilson/Falcon

Films left on contract: at least 2 (Avengers: Infinity War, Avengers 4)

Although he's unlikely to take up the shield like Sam Wilson in the comics, Anthony Mackie has still become an essential part of Captain America's team since his introduction in Age of Ultron and Civil War. He's back in Infinity War and, while the actor hasn't divulged the length of his contract, he has said it extends beyond that and Falcon won't die in the team-up. It probably isn't as hefty as Stan's, but he's likely to live beyond Steve Rogers.

Captain America's ing Characters

Emily VanCamp has a multi-picture deal, with her roles in The Winter Soldier and Civil War setting up Sharon Carter, although whether Marvel will use her depends on how long Chris Evans sticks around.

Despite being a different sort of character, Hugo Weaving is in a similar boat, with a contractual obligation to return but no interest yet by the studio.

Chris Hemsworth - Thor

Films left on contract: 3 (Thor: Ragnarok, Avengers: Infinity War, Avengers 4)

Like Evans, Chris Hemsworth appears to have been given the standard six film contract, saying around the release of Age of Ultron he had only one Thor and two Avengers movies to go (Ragnarok and Infinity War/4 respectively). Unlike Evans, he's made little comment on his thoughts on the future, so whether someone else will become worthy or he'll be coerced to come back for more is unknown.

Tom Hiddleston - Loki

Films left on contract: 3 (Thor: Ragnarok, Avengers: Infinity War, Avengers 4)

Tom Hiddleston originally signed a six-movie contract, which covers his essential role in the Thor trilogy and parts in the first three Avengers films (he wasn't in Age of Ultron, but did film a scene). Presumably, he's had similar contract extension as he's also set for Avengers 4. His future beyond that depends both on whether Marvel want to finally off the character (after multiple death fakeouts) and what the plans are for Chris Hemsworth - you can't really have Loki without Thor.

Thor's ing Characters

Idris Elba hasn't revealed the length of his contract but is now on his fourth film with Ragnarok. If Infinity Stone rumors are true then he may only have one or two turns left.

Stellan Skarsgard has a five-film contract, which he'll round off with Avengers: Infinity War. Fellow human Kat Dennings also had other films set, but looks unlikely to return.

Anthony Hopkins will be back as Odin in Thor: Ragnarok, his third film in the series. What this says of his contract is unknown.