Leonardo DiCaprio

The 'Titanic' star is famous for his method acting approach and is thought to never break character while on set. For 2015's 'The Revenant', he camped out in the wilderness in freezing temperatures, slept in animal carcasses and ate raw bison.

He said: "I can name 30 or 40 sequences that were some of the most difficult things I’ve ever had to do.

"Whether it’s going in and out of frozen rivers, or sleeping in animal carcasses, or what I ate on set. [I was] enduring freezing cold and possible hypothermia constantly."