He's a major British acting talent, who is highly selective about the projects in which he appears - and is also noted for thoroughly immersing himself in his character.
So David Thewlis was never about to star in a Disney film lightly - after all, they are usually more associated with fairytale happy endings, rather than stories about the Holocaust.
Thewlis, who was born and brought up in Blackpool, plays the Nazi commandant of a death camp, whose son Bruno befriends a Jewish boy on the other side of the barbed wire fence.
The Boy In The Striped Pyjamas deals with the horrors seen through a child's eyes and is an adaptation of John Boyne's award-winning novel.
"Some people see the word Disney attached to the film and think it's going to be this saccharine telling of John Boyne's story, but it's a fairly faithful adaptation of the book," says David, 45.
"A lot of people cry at the end because it's pretty grim but there's no other way of doing that ending and it would be terrible if somehow it was changed to be happy.
"It's very important that it's not seen as a sentimental film because it's not a sentimental subject matter."
Bruno, played by Asa Butterfield, and his family move from Berlin to a house in the country - and the eight-year-old sees what he thinks is a farm from his bedroom window.
Bored and lonely, Bruno defies his parents' wishes to stay near the house and sets off through woods to make friends at the 'farm', where he meets Shmuel (newcomer Jack Scanlon), a Jewish boy his own age.
As their friendship develops, Bruno starts learning more about the adult world but his innocent offer to help Shmuel find his father has horrific consequences.
Playing a Nazi commandant would be a daunting task for any actor, but David accepted the role the same day he received the script - partly because of its stark conclusion.
"I was sent the script to my computer and I didn't have a printer with me, so I read it on a PDF file, which made the ending all the more shocking, because I couldn't tell when I was getting to the end. I just kept pressing the scroll button, thinking 'you can't just finish the film there. Is that it? Oh God!'
"But that really attracted me to it, because I thought it was very brave to make a film that had such a final ending, there's nothing more to say after that, there's no discussion to be had. It's like roll the credits and go home and think about it."
While Bruno is sneaking off to see Shmuel, his mother Elsa (Vera Farmiga) realises the nearby camp is not just a work camp after a sick joke from her husband's shady right-hand man Lt Kotler (Rupert Friend).
She slowly starts to unravel as she acknowledges the evil that her loving husband is capable of.
For David, it was a challenge to play someone both human and caring as a father, but also a mass murderer.
"I think it would have been harder to play him just as a monster, who's abusive to his children and rules with an iron rod. It wouldn't be such an interesting film because it's about Bruno's love for his father.
"No matter what he finds out, he cannot believe his father is capable of what's being implied, right up to the very end, he still can't accept that his father is part of this."
David, who won a best actor award at Cannes for his role as a rapist in 1993's Naked, dedicated himself to the role, poring over books and documentaries about the holocaust.
"I read pretty much anything I could get my hands on. The best piece of research was Rudolph Hoess' autobiography, Commandant Of Ausch-witz, which he was ordered to write between his trial and his execution.
"Hoess used to look through a peephole in the gas chambers to see how they died, just to see if it was cost-effective and how much pain they went through.
"But he also had five children who were raised in the compound in sight of the crematoria and he talks in his book about his great love for his children. That's the challenge to show that in the film.
"The only way I could really get my head into playing such a character was just to try and immerse myself in the rhetoric and the imagery of the period and try and desensitise myself to it.
"So I also watched a lot of explicit footage just to try and imagine how these people were capable of it.
"I was oblivious to anything else that was going on, not reading any contemporary newspapers or present-day television, just watching all that, so my head was very black and white and dark."
Besides all the research, David got up each morning during filming and worked out at the gym to make himself feel like a soldier.
"I kind of had a military regime. I was very strict about eating, I didn't drink - I was very disciplined."
The way David talks about his preparation, it's hard to imagine he could have raised a smile during filming, but he says the shoot in Hungary was actually quite light-hearted.
"We were all great friends and the kids, never mind what you see on screen, are actually quite comical. They weren't like 'we're making a film about the holocaust, we must be good'. Asa and Amber, who plays Bruno's sister Gretel, were just so mischevious and funny.''
The children apparently took over the lifts in the hotel one night, in a game of 'hide the shoe' and in breaks from filming David joined in playing 'batty books', making up humorous book titles and authors using names from the cast and crew.
"In between takes we were just being silly like that and cracking up. It sounds strange but we spent a lot of time laughing, cos you're making a film with kids - it was kind of nice."
David, well-known among 'tweens' as werewolf Professor Lupin in Harry Potter, is no stranger to working with child actors, and despite the cliche about never working with children or animals, he says he wouldn't change it for the world.
"People say is it hard to work with kids and I say 'no, I love it', because it makes you younger."
David lived on Harrowside in Blackpool, went to the resort's Highfield high school and appeared in several rock bands around Blackpool - including summer season hotel bookings. He was then known as David Wheeler, or by his nickname Squee.
He then moved to London and trained at the Guildhall School of Music and Drama before taking on small roles in TV shows.
It was his first major film role in Naked that brought him to national attention and he went on to appear in films like Seven Years In Tibet and the Harry Potter franchise.
He was married briefly in the '90s but in 2001 started seeing actress Anna Friel, who gave birth to their daughter Gracie in 2005.
His next film, an adaptation of Paulo Coehlo's Veronika Decides To Die, was shot in New York and earned him a three-year working visa to the States, which came in handy since Anna is currently carving out a niche as a TV actress in LA in quirky comedy Pushing Daisies.
He says fatherhood hasn't changed the way he chooses his roles and he would be happy for Gracie to see The Boy In The Striped Pyjamas when she's a bit older.
"She did see a bit of it the other day. I had the DVD - she's always attracted to films with children in and I didn't stop her from watching it, up to a point.
"When it started to get a little darker I had her out of the room, but when she's 10 I would definitely want her to watch it, as all children should.
"It's educational and it's that old cliche of we must never forget that this happened and that means teaching children about prejudice."
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