Samuel L. Jackson faced the sack when he turned up for work on The Legend of Tarzan set because he was too skinny.

The Pulp Fiction star, who portrays real-life American adventurer George Washington Williams in the new film, lost over 30 pounds (13.6 kilograms) on a strict vegan diet for a film he was shooting in Germany and when he met up with Tarzan director David Yates he looked like a shadow of the man he was when the two first met months before.

"When David and I first met and he cast me I looked one way and then I went off to Germany to do this other film and when I got back to London I'd lost 30 pounds," Sam tells WENN.

"My agent called and said, 'They're gonna fire you if you don't gain 20 pounds! They want you to be formidable'. I went and bought a burger and stopped being a vegan pretty much immediately!"

And while his co-stars, Margot Robbie and Alexander Skarsgard, were on strict diets for the duration of the film, Jackson enjoyed daily feasts.

"I had the same dietitian they had, but they were giving me food!" he laughs.

The actor had no idea how important his character was in history until he started making the movie and researching Williams.

"I didn't know he was a real guy," he adds. "David sent me all this source material and I was totally captivated by it. Then I read King Leopold's Ghost and realised how serious all of this was. It was one of the first real holocausts that occurred on this planet and Leopold was responsible for it.

"All of a sudden I realised I'm not just playing some adventure guy with a pair of big guns; I'm playing a really important person. Luckily last year I was in Blackpool shooting a film for Tim Burton and I actually got to visit his grave in Liverpool, which was kind of profound and moving. Hopefully people will be intrigued enough by him to read those books or to investigate who he really was."

George William Washington was an American Civil War soldier, Christian minister and politician, who documented Belgian leader King Leopold II's takeover of the Congo Free State in Africa in the late 1800s. Millions of people lost their lives at the hands of Leopold's envoys and agents.

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