Oct. 3 (UPI) -- As a former wrestler, Dwayne Johnson has made an acting career for himself by playing strong and physically imposing characters on screen.
But transforming into former MMA and UFC fighter Mark Kerr for the new film The Smashing Machine required Johnson to put on an additional 30 pounds of muscle. After a wig and 22 prosthetics, Johnson is nearly unrecognizable in the role as Kerr, a two-time UFC Heavyweight Tournament Champion.
The Smashing Machine, which follows Kerr's career as well as his personal struggles with addiction, comes to theaters Friday. The film also stars Emily Blunt as Kerr's wife, Dawn Staples, and is directed by Benny Safdie.
Johnson's not the only actor to take on the physical transformation required to portray some of history's most iconic fighters.
Here's a look at seven other actors who got in shape to play legendary MMA fighters and boxers:
