In order to play the role of Nebula in 2014’s “Guardians of the Galaxy,” Karen Gillan had to shave her head and remain bald throughout the film’s shooting schedule.

When Gillan returned to reprise her role as Amy Pond in the sci-fi series “Doctor Who” in 2013, she still had a shaved head from “Galaxy,” but her Pond character required hair.

“Doctor Who” showrunner Steven Moffat was anxious due to Gillan's baldness from “Guardians,” until she returned wearing a wig made of the very hair that her stylists had cut off.

Gillan, wanting to keep a style close to her preferred look, opted to keep her hair and have it woven into a wig for everyday use, and she surprised Moffat with it in “Doctor Who.”

It's notable that Gillan sports an incredibly vibrant shade of red hair, and there is dialogue throughout the series in “Doctor Who” that makes frequent reference to it.