As an actor, when you get tapped to play a superhero, there's no more joking around -- things get serious. You have to give up alcohol entirely, your diet consists of chicken breast, steamed broccoli and protein shakes. You spend hours each day in the gym, all in the name of the movie. You have countless fans of the character that will destroy you if you're not up to par with their expectations regarding the character, and a lot of these actors work day and night to make sure they look the part.

RELATED: Double Duty: 15 Actors Who Were in Both Marvel and DC Movies

It's a lot of stress on the actor who has to get in peak physical form in a short amount of time. It's not like they are cast 10 years before they film the movie and they have all that time to get in shape -- they usually don't have more that 6 months. And if you're not in the best shape, it's a huge challenge. But when you get the chance to be a billion dollar franchise, you'll do everything it takes to be in the best shape humanly possible. Let's take a look at 15 actors who completely transformed their body for a superhero film (in no particular order).

15 HUGH JACKMAN

Would anyone have ever believed that a tall, gangly Broadway singer could play a fantastic Wolverine and actually look like the character? Absolutely not. Brian Singer had enough faith in him to cast him in X-Men and it totally paid off. People tend to forget Jackman's theatre origins, because he's become such a massive star since his first outing as Wolverine.

With each passing film, he manages to get in better shape, which is no small feat for a man who has hit his late 40s. He has really hit his peak over the last few films, specifically in The Wolverine. His physique in that film was beyond comparison to any other actor. He became incredibly lean and ripped for the film and his vascularity is absolutely ridiculous.

14 TOM HOLLAND

How did that skinny little kid that made his first big break in the disaster movie The Impossible, which told the story of a tourist family who lived through the 2004 Indian Ocean tsunami, become the shredded Peter Parker in Spider-Man: Homecoming? Turns out, not surprisingly, with a lot of hard work. He actually has a background in dance, taking classes at a very young age. He is also into free running, which he does often with his friends.

He even has a long history of practicing gymnastics, which is certainly a huge advantage for someone who portrays the web-slinger. His training might have actually helped him to get the role, as his audition tape included him summersaulting in and out of frame. For Spider-Man he took his training further by implementing a circuit training regimen, electronic muscle stimulation and boxing.

13 CHRIS PRATT

Chris Pratt used to be known as the loveable oaf Andy Dwyer on Parks & Recreation but that image was completely transformed overnight when people got a look at him topless in the trailer for Guardians of the Galaxy where he looked totally jacked and totally ripped.

Pratt was no stranger to getting into shape for a role, as he had previously done so for Moneyball and Zero Dark Thirty, but to play Star-Lord, he took his training to another level and the results were incredible. His diet was extremely carefully calculated, eating 4,000 calories and he worked out five days a week. In the eight months leading up to shooting, he shed over 60 pounds and gained quite a significant amount of muscle to add to his frame.

12 GAL GADOT

A lot of fans were outraged when Gal Gadot was first cast as Wonder Woman. They assumed that the actress, who most had only seen in the Fast and Furious franchise, couldn't possibly live up to their wildest Wonder Woman dreams. One of their arguments was that she was far too skinny for the part. Given her history as a model, we understand those concerns. Luckily they were completely off base.

To prepare for the role, she trained in various disciplines including capoeira, swordsmanship and Brazilian jiu-jitsu. Of her training regimen, Gadot stated on Live with Kelly & Ryan: "I was training for six months prior to the shoots, and six hours a day. I did two hours [of] gym work, two hours [of] fight choreography and one and a half hours to two hours horseback riding." Her hard work paid off because she looked incredible in both of her appearances.

11 RYAN REYNOLDS

Ryan Reynolds has been in incredible shape long before he took the role of Deadpool. In fact, he's been in consistently excellent shape because of the various superhero roles he took over the years demanded that he stay that way. Before Deadpool, he was Green Lantern, and before that he made his shredded superhero debut in Blade Trinity as Hannibal King.

Reynolds gained 25 pounds of muscle and was down to 4% body fat for the role, which is borderline dangerous as your body needs a minimum about of fat to function properly. Before that, Reynolds claims he was headed down a very unhealthy path, as he was completely careless about what he ate or drank. Since Blade, he has maintained his healthy lifestyle not only for his superhero roles, but for himself.

10 GERARD BUTLER

Gerard Butler worked out diligently for the seven months leading up to the shoot for 300 where he played King Leonidas and the results speak for themselves. He had to lose fat and gain muscle to be a believeable Spartan king. Butler maxed out at about 200 pounds for the role. At 6'2, his imposing physique made him the perfect casting choice.

A huge part of his routine was the infamous 300 workout, which consists of 300 repetitions of different exercises and includes 50 reps of 135 pound deadlifts, 50 pull-ups, 50 push-ups and quite a few other sets of 50. If that doesn't sound too bad to you it's because we left out the best part: the actors on the set of the film had to complete the routine without rest.

9 HENRY CAVILL

Say what you will of Superman in the DCEU, but absolutely no one can dispute that Henry Cavill looks the part. The man looks like a Jim Lee drawing brought to life. For his previous role in Immortals, Cavill weighed in at 170 pounds. By the time filming for Man of Steel started 5 months after being cast, he hit 190.

During his bulking phase, he ate between 5,000 and 6,000 calories a day. Cavill stated that his defining moment that made him become Superman was during a workout where he was front squatting 305 pounds. After pumping out three sets of four repetitions, He froze at the bottom of the third rep of his fourth and final set. He could have thrown the bar down but instead he pushed through. That intense determination is exactly what got him into Superman shape.

8 J.K. SIMMONS

When images appeared online recently of 61-year-old J.K. Simmons working out at the gym with a big bushy beard and massive arms on display, the internet lost it. He had just been cast as Jim Gordon in Justice League and fans couldn't believe the shape he was in.

Only later did fans find out that Simmons isn't even getting in shape for the role. He stated that he is only doing it to stay in shape for personal reasons. It just so happened that he was starting filming on the superhero flick but it was pure coincidence. He looks so massive in the pictures that he could probably beat down Batman if he had to. This is a Commissioner Gordon like we've never seen before.

7 CHRIS EVANS

When you look over Chris Evans' filmography prior to taking the role of Captain America, it is clear that he was already in pretty damn good shape. He had already played Johnny Storm in Fantastic Four, so he was no stranger to the training regimen required for a superhero role.

The slim actor gained 30 pounds for the role and admits it was an extremely difficult process. His efforts in the gym were so excessive that he would end up throwing up from the strain. His workout was meant to be functional so that he could remain flexible and agile. It consisted of gymnastics and gruelling three day split weight training sessions which allowed him to concentrate on specific muscle groups. His diet was extremely high in protein with some complex carbohydrates.

6 TOM HARDY

Tom Hardy is an incredibly physical actor. He is able to express a lot of intensity without even uttering a word and that intensity is extremely apparent in every one of his roles. When he was cast as Bane in The Dark Knight Rises, some were skeptical not because he lacked the acting chops, but because he might not have the sheer size required for the role. Shorter than Christian Bale by three inches, many thought he just couldn't cut it as the massive brute Bane, but he proved everyone wrong.

Hardy gained 30 pounds, getting his weight up to 200. He also prepared for the role by learning various fight styles for the different action sequences. His weight gain affected another film he was shooting at the time of his prep for the Batman film: Lawless, where his character was supposed to be significantly slimmer.

5 JESSICA BIEL

How do you manage to prevent getting typecast after playing the same character on a family-friendly television show for a decade? For Jessica Biel, it was simple: become an action star. But the road from fresh faced daughter of a reverend on 7th Heaven to vampire slayer in Blade Trinity wasn't an easy one.

She trained four hours a day, seven days a week. This regimen included over an hour and a half of weight training and cardio, followed by an hour of martial arts training and an hour of archery. She would eat six to eight small meals a day and was able to get down to 8% body fat. As a result of all her hard work, she looked completely killer in the movie and she was entirely believable as a person capable of slaying a gang of vampires.

4 CHRIS HEMSWORTH

In Chris Hemsworth's case, it's pretty simple. He was going to play a Norse god so he had to look the part. At 6'3, he already had the height to play an imposing figure like Thor but he lacked the muscle of his comic book counterpart. With such long limbs, it must have been an incredibly difficult uphill battle to achieve the amount of gains he managed to amass for the role especially considering his slim frame.

Back in 2009, we got a good look at Hemsworth's physique in A Perfect Getaway. It was clear that he was in good shape, but he still needed to bulk up a considerable amount to play Thor. He was able to bulk up to 215 pounds, but then quickly shed 30 to play in the Formula 1 film Rush, only to bulk back up again for the Thor sequel all within a year.

3 JARED LETO

Jared Leto's costume design and makeup wasn't well received in Suicide Squad because a lot of people argued that he looked more like a gangster or a pimp than he did The Joker. One thing people did agree on however was that he got in incredible shape for the role.

Leto is no stranger to changing his body drastically for a role. For Chapter 27, where he played Mark David Chapman, the man who inexplicably murdered John Lennon in cold blood, Leto gained 67 pounds of fat for the role and found himself in a wheelchair due to the excessive weight gain. For Dallas Buyers Club, he went in the opposite direction and lost 30 pounds off of his already thin frame. As for his role as The Joker, we have never seen him this ripped.

2 MICHAEL B. JORDAN

Michael B. Jordan got in incredible shape once before to play Apollo Creed's son in the Rocky sequel Creed. Although he always looked like an active guy before, he really wowed audiences in Creed with his exceptional physique. For Black Panther, where he plays Erik Killmonger, he had to prove that his take on the supervillain would physically look like a match for T'Challa.

People tend to think that once you get in shape you stay that way, but that is not the case at all. A lot of muscle is lost if you don't maintain the same level of effort. If his Creed workout is any indication (which included an hour of cardio, weight training and boxing six days a week), he was put through the ringer to play Killmonger.

1 CHRISTIAN BALE

No body transformation list could be complete without Christian Bale. The number of times this guy has completely altered his body for a role is staggering. Before obtaining the role of Bruce Wayne in Christopher Nolan's origin story Batman Begins, Bale practically became a walking skeleton to play a mentally unstable insomniac in The Machinist.

He was down to 120 pounds and he bulked up to 220 in a mere six months, actually getting bigger than what Nolan had anticipated and Bale had to lose some weight. Luckily for Bale, he was in incredible shape in American Psycho and his muscle memory allowed him to gain the muscle back a lot faster. Bale went on to lose considerable amount of weight between his other Batman films in Rescue Dawn and The Fighter only to gain the muscle back once again.

Which of these transformations is the most shocking? Let us know in the comments!