Some film roles can be harder to tackle than others. So hard, that once the actor or actress has found it, there’s no way to be anything but the character they’re playing. That can usually result in a more powerful performance – but it doesn’t mean it’s easy on their co-stars, or the crew behind the scenes.

Here are 10 Method Actors Who Refused to Break Character.

Meryl Streep

It was intimidating enough for Anne Hathaway to share the screen with Meryl Streep in The Devil Wears Prada, but the Oscar winner approached the young actress on their very first day of shooting, telling her she was perfect for the role. She then added that was the last time she would be nice to her. And it was. It wasn’t until promoting the film months later that Hathaway actually got to meet the actress, ¬†instead of the cold fashion icon she played in the film.

Joaquin Phoenix

When it comes to playing an actual celebrity in a dramatic biopic, losing yourself in the source material is almost always the way to go. So when Joaquin Phoenix refused to lip sync, instead learning to play guitar and sing just like Johnny Cash in Walk The Line, he took the extra step of playing the part between takes, asking cast and crew to refer to him by his character’s name. He would later say he felt like an idiot for the demand, but at the time, hearing someone call for “Joaquin” didn’t feel right – and it’s actually easy to see what he meant.

Tom Hardy

Not every actor could have made a real character out of the grunting, shifty-eyed Max in Fury Road, but Tom Hardy made his handful of lines and frantic gestures count – even between takes. During filming, reports surfaced that Hardy wasn’t easy to work with, remaining in character, muttering to himself and not engaging in conversation with his co-stars or director. But it’s hard to argue with any of the results.

Jim Carrey

You might think that the weird and wacky actor isn’t too different from the characters he plays, but for the Andy Kauffman biopic Man on The Moon, Jim Carrey lost himself in the strange comedian completely. He portrayed Kauffman and his alter ego, Tony Clifton, the entire time the film was being shot. The cameras rolled as he did, capturing over 200 hours of Carrey ambushing crew members and extras, with some of it making it into the finished film.

Adam Driver

Sometimes, pain or discomfort experienced during filming is just what’s needed to get an actor to the right place and attitude for the role. For Star Wars: the Force Awakens, it was the vision-obscuring mask of Kylo Ren that actor Adam Driver had troubles with. He joked that the cast was a mystery even to him, since he couldn’t seen any of them during filming, but he stayed in character throughout most of the shoot. That meant keeping the helmet on between scenes, using the confusion and isolation feed his character.

Robert Downey, Jr.

It’s still hard to believe that Robert Downey, Jr.’s role as Kirk Lazarus in Tropic Thunder got him an Oscar nomination, but you can’t say he wasn’t committed to the part. Apparently, he remained in character as Lazarus — or, as the actor Lazarus, in character as Staff Sergeant Lincloln Osiris – during the entire shoot. And just as Lazarus claimed he didn’t drop character until after the DVD commentary, neither does Downey, recording it as Lazarus AND Osiris, the role within a role.

Christian Bale

He’s known for staying in almost every character he plays, but for his major American debut in Batman Begins, Christian Bale went a step further. Aside from having his trailer labelled as “Bruce Wayne’s,” he took his American accent and personality all the way through press interview and promotion for the film. Even fans who had watched hours of the Welsh actor discussing the part had no idea that he wasn’t an American – which may have helped win over fans of the Gotham playboy from the start.

Jared Leto

His on set antics as the Suicide Squad’s Joker got plenty of headlines, but Jared Leto was losing himself in roles long before. Leaving behind the character of Rayon in The Dallas Buyer’s Club wasn’t easy, having lost 30 pounds and waxed his entire body. So Leto remained in character in all aspects of his life while shooting, with the director even admitting that he didn’t know Jared Leto, only the character he played.

Tom Hanks

He isn’t known for his method acting, but when playing the star prison guard of The Green Mile, Tom Hanks felt some extra dedication was needed. When Stephen King visited the set to see the movie based on his own novel, Hanks felt it was a compliment to remain in the character King had created. Giving the author a tour of the prison, he even refused when King asked fi he wanted to take a turn sitting in the prop electric chair, explaining that the head of the wing shouldn’t be seen playing around by the guards looking up to him.

Daniel Day-Lewis AND Sally Field

How about a two-for-one? Daniel Day-Lewis is famous for his extreme method acting, but he met his match with Sally Field, the Mary Todd to his Abraham Lincoln in the Steven Spielberg biopic. Field turned inward into the role, texting her co-star using the language of the time, with Day-Lewis going one step further, retaining his American accent while on set, and even signing his texts as the former President.