They've got a team on hand to make sure they're always looking their best - but sometimes Hollywood stars need to ditch the glam to land movie roles.
Plenty of our favourite stars - including Kaley Cuoco, Ryan Reynolds, Anne Hathaway and Jennifer Aniston - have undergone complete transformations for their pay cheque.
Some of the changes were real, others were made using clever behind-the-scenes tricks like prosthetics, but either way - the results are staggering.
To check out some of the most dramatic makeovers (or makeunders), see below:
