The young star plays the monster maker's sidekick Igor in the latest incarnation of Mary Shelley's gothic horror tale, and chose to embrace the physical challenge of playing a deformed man.

"If you do something that puts you in a little bit of pain, it makes you feel as though you're working slightly harder than you normally do as an actor," Radcliffe tells Playboy magazine.

"I did the play The Cripple of Inishmaan for four months in London and never had any physical problems. Doing what I did on Frankenstein for three weeks was a f**ker. There's a crick in my neck now that was not there before."