The top five most dramatic celeb film transformations!

With such strict ideals of beauty in Hollywood, it's rare to see someone step outside of the blonde, sunkissed norm.

But when a gritty role called for a complete image overhaul, these actors stepped up to the post.

Here's our look at five of the most dramatic changes actors and actresses have undertaken for film roles. Weight loss, weight gain, head shaving, piercings… it's all there!

1. Charlize Theron for Monster
In what is perhaps one of the most memorable celebrity transformations of all time, Charlize packed on 30 pounds to play prostitute-turned-serial killer Aileen Wuornos. Her efforts earned her an Oscar, so it wasn't all bad!

2. Matthew McConaughey for Dallas Buyers Club
Matthew had to undergo gruelling diet changes to drop muscle and body fat for the role of Ron Woodroof. The transformation was scary:

3. Rooney Mara for The Girl With The Dragon Tattoo
Rooney chopped her hair, bleached her eyebrows and got several piercings to fully embody to role of tough girl hacker Lisbeth Salander in the US version of this film. "The eyebrows were the biggest shock because that really changed my face, and I didn't recognise myself," she told Vogue at the time.

4. Hilary Swank for Boys Don't Cry
Hilary was relatively unknown when she took on the role of Brandon Teena, a woman living as a man, for Boys Don't Cry. She dropped her body fat down to 7 percent and spent months dressing as a man in preparation for the role, which earned her a Best Actress Oscar.

5. Tom Hanks for Castaway
A year-long break in filming was needed to give Tom Hanks time to drop from his normal starting weight down to a Castaway-esque skinny frame. The actor dropped 50 pounds and grew out his hair and beard – yes, it's all real!