This post deals with mental health issues and may be triggering for some readers.
When it comes to acting, celebrities have to spend quite a lot of time preparing for a role and getting into character.
But behind the scenes, playing a particular role can leave a mark on even the most experienced actors.
From nightmares, to weight loss and mental health issues, acting can often take a physical and emotional toll on celebrities which can continue to affect them even after they leave the set.
Watch: The auditions that scored actors their leading roles. Post continues below.
From Margot Robbie in I, Tonya to Shelley Duvall in The Shinning, here are eight times actors were seriously affected by their roles.