The Marvel Cinematic Universe celebrated its 10th anniversary in 2018 with the release of three films: Black Panther, Ant-Man and the Wasp, and Avengers: Infinity War. The three movies combined made over $4 billion at the worldwide box-office, with over $2 billion of that coming from Infinity War alone. Black Panther was also a genuine cultural phenomenon, a movie event that proved massively important for black representation and inclusion, while also giving the world some of the best characters the MCU has had to offer. At this point, it feels like the MCU is too big to flop, as Marvel has hit upon a formula that delivers consistently good-to-great movies that all further the overall interconnected story Marvel is telling. It's an unprecedented feat that Marvel has accomplished and the success shows no signs of slowing down.

Fittingly then, many of Hollywood's A-listers are involved in the MCU and many more are sure to join along the way. Playing Tony Stark/Iron Man has made Robert Downey, Jr. an icon and one of the highest paid actors in history, and the MCU has made stars out of the likes of Chris Hemsworth, Scarlett Johansson, Chris Evans, and Chris Pratt. Even elder Hollywood icons such as Robert Redford, Michael Douglas, and Michelle Pfeiffer have become entwined in the MCU, which goes some way to showing the power Marvel wields in Hollywood. It also stands to reason that there are certain rules and regulations that actors must abide by if they want to be welcomed into Marvel's embrace, and these rules only increased with the 2009 purchase of Marvel Entertainment by Disney. With the House Of Mouse calling the shots, things jumped up several notches, and these are 20 Weird Rules Every MCU Actor Has To Follow.

20 THOU SHALT NOT APPEAR IN MOVIES FROM THE DISTINGUISHED COMPETITION

This first rule should be taken with a pinch of salt, as the source is a one word response at a comic book convention and there has been no official confirmation of it. But, it's a juicy tidbit if it is true. At the 2017 Supernova Comic-Con in his native Australia, Chris Hemsworth was quoted as saying it is “illegal” for an MCU actor to appear in a DC film. Marvel head honcho Kevin Feige had previously said that there were no restrictions on MCU actors playing other superheroes (when asked about Josh Brolin playing Thanos and Cable), but in that situation, the rival character was another Marvel one in a Fox film. Adewale Akinnuoye-Agbaje also played Killer Croc in Suicide Squad after appearing in Thor: The Dark World, which would seem to contradict Hemsworth.

19 REVEALING PLOT SPOILERS IN INTERVIEWS? BIG NO-NO

The plot details of every MCU movie are closely guarded nuggets. These are massive movies with huge budgets and no one wants to risk story elements getting out there that could affect the bottom line in any way. But, at the same time, the movie's need to be promoted and interviewers will always be keen to land a scoop, so sometimes, the actors face very probing questions. Tom Holland seems to be one of the worst offenders in the MCU when it comes to letting important details slip, so much so that Marvel played into it during the Avengers: Infinity War press engagements and poked fun at Holland's inability to keep information close to the chest. They even paired him with Benedict Cumberbatch, known to be good at dancing around spoilers, in order to keep him in check!

18 EXTENSIVE BACKGROUND CHECKS ARE CONDUCTED ON PROSPECTIVE MCU ACTORS

Whenever Disney signs up an actor for an MCU role, no matter how seemingly small, extensive background checks are conducted in order to unearth any potential skeletons in their closet. Tom Vaughan-Lawlor, an Irish actor who played Ebony Maw in Avengers: Infinity War (with the use of motion capture technology), was interviewed on RTE Radio 1's Second Captains show and talked about how amazing the movie was to be a part of, but indicated that he was nervous about what he could and couldn't say about the movie due to all the waivers and contracts he had signed. He then said they did background checks on him to make sure they weren't “hiring someone with weird baggage” or someone likely to leak things on social media.

17 TOO MANY “CREATIVE DIFFERENCES” OR MONEY DISPUTES? YOU'RE OUT

These days, Marvel has ironed out any kinks in their creative process and most actors that work with them know the deal when they sign up: namely, when it comes to their characters, what Marvel says goes. However, in the early days of the MCU, there were a few actors who demanded a little too much creative control or were combative with Marvel over money, and they were swiftly removed. Edward Norton clashed with executives on The Incredible Hulk due to the amount of control he exerted over the script and he was replaced by Mark Ruffalo in 2012's The Avengers. Terrence Howard played James Rhodes in Iron Man, but was replaced by Don Cheadle in Iron Man 2 and onwards. He said he was lowballed by the studio in contract negotiations.

16 ACTORS ARE EXPECTED TO HIT THE GYM AND KEEP THEMSELVES IN TIP-TOP PHYSICAL SHAPE

The guys and gals of the MCU are a pretty fit bunch, by and large. They're playing superheroes, after all, and maintaining their heroic bodies is the name of the game. Chris Pratt famously went through a complete body transformation when he got the role of Star-Lord in Guardians Of The Galaxy. Known as a slightly plump comedian, he worked out judiciously to lose weight and tone up and has been remarkably candid in interviews about the process. He said it's all about consistency and admitted that he will work out harder if he knows he has a photoshoot coming up. Scarlett Johansson said that getting up at 5:00 a.m. to train and eating nothing but salad and chicken is boring, but she has to do it to look the part of Black Widow.

15 YOU WILL HAVE EXTENSIVE FIGHT TRAINING AND CHOREOGRAPHY TO LEARN

As well as hitting the gym to ensure they look like superheroes on screen, many MCU actors will also be expected to take part in extensive fight training exercises for the movie's action scenes. For Black Panther, Chadwick Boseman was trained in martial arts by Marrese Crump in Tampa, Florida. He also worked with jiu-jitsu Grand Master Bill McCloud in Brooklyn, New York, and later attended a fight camp with Marvel's fight choreographers before filming began. This was all on top of the already enduring five-hour workouts with a conditioning coach that he underwent for months on end! It's obvious that signing up for an MCU role may very well entail far more than simply acting or wearing an uncomfortable costume, but it all pays off in the end.

14 SOME ACTORS WILL HAVE TO ENDURE A LENGTHY MAKE-UP PROCESS

Some characters in the MCU look very, very different from garden-variety human beings, so in order to play them, the actors may have to be put through a time-consuming make-up/prosthetics process. Karen Gillan, the actress who plays alien Nebula in the Guardians Of The Galaxy movies, shaved her head completely bald and endured four hours and 15 minutes in the make-up chair every morning on the first film. She had to have a five-part prosthetic applied and also wore 22-millimeter contact lenses. Thankfully, the process was refined on the sequel and her time in the chair was reduced to two and a half hours and only the back of her head being shaved. Either way, that's still a lot to go through before you even start your working day!

13 YOU ARE CONTRACTUALLY OBLIGATED TO GO ON MASSIVE GLOBAL PRESS TOURS

Once a movie is finished, MCU actors are contractually obliged to promote it. For a behemoth as massive as the MCU, this entails an elaborate and lengthy global press tour. Now, being flown to exotic locations to walk red-carpets at premieres and take part in interviews talking about the awesome stuff that you've been filming sounds like a lot of fun, and we're sure it is... for a while. But, it is also a double-edged sword, as fatigue can set in pretty badly with the constant travel and the fact that you will almost certainly be forced to answer the same questions hundreds of times over from every different media outlet in every country. There are harder ways to make a living, for sure, but it's not hard to see how a press tour could wind up very exhausting for an actor.

12 YOU ARE CONTRACTUALLY OBLIGATED TO APPEAR FOR RE-SHOOTS AT ANY POINT

Another obligation written into MCU contracts concerns reshoots. Namely, actors must make themselves available for them if called upon. Sometimes, when the director is assembling a film, they might realize they need more shots to make everything flow better, or entire new scenes might need to be filmed to incorporate new story elements. In this case, MCU actors have to come back for the reshoots, no matter what else they're doing. It particularly angered Idris Elba, who publicly spoke of how filming reshoots as Heimdall in Thor: The Dark World, only a day after playing Nelson Mandela in Long Walk To Freedom, didn't sit well with him. His exact words were: “It ripped my heart out”, and that he told his agent “This is [enduring], man. I don't want to do this.” Oh dear!

11 YOU MUST SAY “YES” TO ANY CAMEO APPEARANCES IN OTHER MCU FILMS

For fans, the most exciting thing about the MCU is its interconnectivity. It's just like the comics have always been, with all the beloved heroes and villains existing in the same fictional universe. Their stories can cross over and connect in exciting ways, and characters aren't restricted to appearing in only one series of movies; they can show up anywhere across the MCU. Therefore, the cameos have become a big deal for fans, with everyone delighting at the Captain America Public Service Announcements in Spider-Man: Homecoming, or Sam Wilson/Falcon's hilarious skirmish with Scott Lang in Ant-Man. The MCU actors are contractually obliged to agree to these cameos and they supposedly don't count toward the overall amount of movies they signed up for.

10 YOU WILL BE EXPECTED TO SIGN ON FOR MULTIPLE MOVIES IN ONE CONTRACT

It's common practice for MCU lead actors to sign multi-picture deals. For example, Samuel L. Jackson signed up for a whopping nine films as Nick Fury! The number of movies other actors have on their contracts isn't as well known, though it's been reported that six-film deals are the norm these days. Marvel is keen to sign actors to multiple films because, if they go on to become important members of the Universe, it lessens the need for contract renegotiations at a later date. They've already had this happen with Robert Downey, Jr., the lynchpin of the entire MCU. He initially signed a four-picture deal, but has now appeared in nine MCU films, meaning his contract has been renegotiated multiple times (with a few extra zeroes added on each time, no doubt).

9 RESEARCH IS ENCOURAGED, BUT NOT MANDATORY

One surefire method to win over fans is for an actor to show how much independent research they are doing on the character they've been hired to play. Fans like to think that the actors care about these characters as much as they do, and hearing that they are reading a bunch of the comics on their own time will always go over well. Brie Larson recently shared a picture on Instagram of herself reading a Captain Marvel trade in bed, while wearing Captain Marvel pyjamas. Pretty good, but Benedict Cumberbatch went above and beyond a few years ago when he showed up to a New York comic book store in a full Doctor Strange costume to nab a copy of The Oath. He also spoke in interviews about “avidly” reading the comics. Nicely done, sir!

8 BE PREPARED TO SIGN YOUR LIKENESS RIGHTS AWAY

When a kid (or grown-up geek) buys an Iron Man action figure associated with the movies, they most certainly want it to look like Robert Downey, Jr. Otherwise, it would look like a knock-off, right? Well, in order for this to happen, Mr. Downey, Jr. will have signed his likeness rights away for use in merchandise. The Marvel characters likenesses appear on everything: toys, cereal boxes, posters, statues, models, the list could go on and on. The MCU actors have to make themselves available to Marvel's licensors if they need them; it could be for a session of computer mapping your face for use in a video game, or it could be a public appearance at a product launch. A good agent may be able to get the actor a piece of the merchandising pie, but that's not always guaranteed.

7 YOU WILL BE EXPECTED TO MAINTAIN A GOOD PUBLIC IMAGE

Generally, fans want to believe that the people playing their heroes on the big screen are good people in real life, it's just human nature. We want to believe that these famous actors are relatable and likeable, that they are just like us (only with better paid jobs and high levels of charisma). Disney/Marvel wants their fans to believe that too, which is why all the MCU actors are expected to maintain a good, moral public image. To be fair, most of the Marvel actors do seem like genuinely admirable people, which is why it didn't come off as a publicity stunt when, for example, Chris Pratt and Chris Evans dressed as Star-Lord and Captain America, respectively, to visit a Boston Cancer Charity and a Seattle Children's Hospital. They're just good dudes doing nice things.

6 LET THE STUNT PERFORMERS DO THE STUNTS

Summer 2018 saw the release of Mission: Impossible - Fallout, the latest clear example of Tom Cruise being a stunt enthusiast. Those movies are now largely sold on the back of Cruise's dedication to doing the majority of his own crazy stunts and they are truly spectacles to behold. The 2000s, in general, have seen an increased amount of actors doing as many of their own stunts as they are allowed to do, and it's definitely exciting to watch. But, on the MCU movies, insurance premiums for actors are sky high and the most dangerous stunts are left to the trained professionals. The actors do a lot of their own stuff, but generally don't have the pull of a Tom Cruise, who can convince a studio to let him hang off the side of an airplane as it takes off!

5 DISNEY MANDATES THAT YOUR CHARACTER WILL NEVER, EVER SMOKE ON-SCREEN

In 2001, then Marvel Editor-In-Chief Joe Quesada laid out a policy concerning smoking in Marvel comic books. No main character was allowed to be seen smoking (with Quesada specifically namechecking Wolverine), aside from in the MAX line, where Nick Fury could still have cigars. The Marvel Studios movies never seemed to pay attention to this rule, however, as Obadiah Stane was seen smoking a stogie in Iron Man. However, in 2009, Disney bought Marvel Entertainment and in 2015, Disney CEO Bob Iger announced that they would be enforcing their own in-house “no smoking” rule in the MCU movies going forward. So, unless this rule is relaxed, Sam Jackson's Nick Fury definitely won't be shown lighting up anytime soon!

4 CONFIDENTIALITY IS EVERYTHING, SO YOU WON'T BE ALLOWED TO TAKE A SCRIPT HOME TO READ

Elizabeth Olsen, who plays Wanda Maximoff in the MCU, was interviewed on Jimmy Kimmel Live in April 2018 and revealed some surprising details on Marvel's quest for secrecy regarding Avengers: Infinity War. She said certain cast members were offered the chance to read the full script... in one five-hour sitting, on an iPad, in an empty room, after checking in your cell phone at the door! She thought this process sounded “unpleasant”, so just asked for Marvel to give her Wanda's pages. Some cast members did choose to do the private read, including Robert Downey, Jr. and Benedict Cumberbatch, but Paul Bettany (Vision) then revealed that other cast members were even given fake scripts with erroneous plot twists in order to prevent real details leaking!

3 YOU MAY BE TAKEN TO HIDDEN SHOOTING LOCATIONS IN UNMARKED VANS

Elizabeth Olsen was also refreshingly honest about some of the tactics used by Marvel to maintain privacy while filming Avengers: Infinity War. At Ace Comic Con in Seattle, she and Paul Bettany were interviewed by geek icon Kevin Smith, and Olsen revealed she had absolutely no idea what was supposed to happen during Infinity War's ending until the very day they filmed it! Director's Joe and Anthony Russo bundled all the actors into an air-conditioned van, told them the ending and then revealed they were traveling to the shooting location right then and there. This must be difficult for actors, as they constantly need to be able to adapt and get into their character's headspace on the fly, without all the knowledge that could potentially help their performance.

2 YOU FULFILL YOUR OBLIGATION EVEN IF THE DIRECTOR YOU CHAMPIONED IS LET GO

Natalie Portman's falling out with Marvel Studios has been well publicized and it stands as a great example of what is expected of an actor even if they are not happy with the studio's decisions. Portman championed the hiring of Patty Jenkins to direct Thor: The Dark World and was reportedly deeply upset when Jenkins left the project over creative differences. Jenkins would go on to direct the excellent (and culturally important) Wonder Woman, so her decision not to make a Thor movie that she didn't believe in was best for both parties. But, Portman still had to fulfill her obligation to appear in the movie, which was arguably the worst MCU effort, then, was unceremoniously written out of the MCU with a throwaway line in Thor: Ragnarok.

1 YOU WILL GIVE UP THE MANTLE IF IT'S REQUIRED

When news broke that Marvel and Sony had worked out a deal to allow Spider-Man to appear in the MCU, fans were ecstatic. Finally, Marvel's premier superhero was coming home where he belonged. Andrew Garfield, who had played the character twice in The Amazing Spider-Man movies, didn't return to the role a third time and Tom Holland was cast as the new MCU wall-crawler. While it was supposedly always Marvel's intention to recast and go younger with the role, Garfield was apparently considered and not immediately fired, as many fans believed. However, once a decision had been made by Marvel Studios, the actor had to fall in line with the powers-that-be and allow the mantle to be passed to someone new, whether he truly wanted to or not.