Getting into character can mean digging into a character’s motivations, inner struggles, and history.

It can also mean undergoing major physical transformations.

“Sometimes the physical can portray the psychological,” Robert DeNiro once toldThe Guardian.

Cara Delevingne with pixie cut

“That’s why I put on 60lb when I played Jake LaMotta in ‘Raging Bull.’

I didn’t think using prosthetics would do the same thing.”

Grande’s signature giant ponytail look was born out of necessity.

Ariana Grande before and after

“As one would assume, that completely destroyed my hair.”

At the time, she wasn’t happy with the way her hair looked when she wore it down.

However, there was one hairstyle that got everybody talking in 2010: Emma Watson’s pixie cut.

Emma Watson before and after

Rather, she was ready to say goodbye to Hermione Granger and start her next chapter.

“It was weird.

My hairdresser was like, ‘When are you going to freak out?’

Christian Bale then and now

Most people cry or go into shock,' but I was very calm,” she said."

I knew it was the right thing."

While this change apparently wasn’t everyone’s cup of tea, Watson didn’t seem to mind.

Anne Hathaway before and after

That’s such an error.'

And I was like, ‘Well, honestly, I don’t really care what you think!'"

He stuck to a strict diet of water, coffee, and a single apple per day.

Mila Kunis before and after

In a 2018 interview withThe Guardian, Bale called the severe physical transformation “amazing.”

It’s like you’ve abandoned your body," he said.

“That’s the most Zen-like state I’ve ever been in my life.”

Chris Pratt before and after

To play the DC superhero for the first time, Bale packed on 100 pounds in just months.

As he told HuffPost (viaMen’s Health), “I overdid it because I was enjoying gorging.

I was straight into pizza and ice-cream and eating five meals in a sitting.”

Jonah Hill before and after

Rather, her real-life tresses got a major chop.

“I’m not promoting this at all.

When I gained it back, it went to completely different areas.”

Millie Bobby Brown before after

All the weight that left my chest went to my side hip, my stomach."

For five of the seven seasons, he maintained a less muscular physique for the character.

That all changed when Pratt got the call to join the Marvel Cinematic Universe.

Cara Delevingne before and after

As he told Men’s Health U.K. in 2015 (viaE!

Once he landed his role in “Guardians of the Galaxy,” he started packing on the muscle.

“It’s very hard to explain why Andy Dwyer now looks like a superhero,” he said.

Lady Gaga before and after

After filming wrapped in 2015, he began cutting weight.

I found that Japanese food was very helpful to me," he said.

What’s more, he reached out to his “21 Jump Street” co-star for some tips.

Zac Efron before and after

“Yes, you dumb mother****er,” Tatum said, according to Hill.

“It’s the simplest thing in the entire world.”

In a January 2018 interview withW Magazine, Brown reflected on the significance of that haircut.

“I couldn’t hide behind my hair like I used to.”

It took some time for the actor’s hair to grow back, but it worked for the show.

While her hair was short, Brown had to find other ways to express herself.

Girls can feel like their hair defines who they are, whereas for me, it couldn’t."

In Season 4, fans saw Eleven sport another buzz cut.

Naturally, fans wondered if Brown got another drastic haircut for “Stranger Things.”

However, this time around, the styling department created an ultra-realistic wig for the actor to wear.

That way, she could keep her hair at its current length.

She also established herself as a bona fide style icon who can pull off just about any hairstyle.

In 2017, Delevingne shaved off her long golden locks for “Life in a Year.”

When her hair grew out a bit, she rocked a bleached pixie cut.

However, while promoting “A Star is Born,” the pop icon went full Old Hollywood glamour.

There was the silver Givenchy Haute Couture gown she wore to the “A Star is Born” premiere.

There was the demure white maxi dress she sported at the Venice Film Festival in 2018.

Gaga looked totally different in the movie, too.

In 2019, it was Kumail Nanjiani’s turn.

The post went viral soon after.

“It felt, for a brief moment, powerful.

And then after that, it was by and large negative.

It felt naked, it felt vulnerable,” Nanjiani shared.

That became my primary goal, it was just kind of centered around achieving that aesthetic."

“I don’t think I’ll ever be the same after playing Kevin.

It definitely changed me; I’m still coming back to Zac,” he said.