Former Doctor Who star Karen Gillan has shaved her head for her role in Guardians of the Galaxy.

The 25-year-old actress showed-off her new look during the Marvel Studios Press Line at Comic-Con 2013 on Saturday evening (July 20).

Speaking about her new hairstyle, Gillan said: "It's liberating. I think everyone here should shave their heads."

Karen arrived at Comic-Con with a full head of hair on Friday, which was later revealed to be a wig.

Gillan is set to play an alien supervillan called Nebula in the upcoming Marvel adventure, who tries to wipe out entire civilisations.

Guardians of the Galaxy will be released on August 1, 2014.