9. Gillian Anderson
Natural hair color: A dark or dirty blonde
Why she went red: Secondhand accounts suggest it was for her career-making role in The X-Files. In rehearsals for the show, Anderson wasn't a redhead, and her character Agent Scully wasn't a redhead in the scripts. But by the time the show was filmed and aired, she was. Is this fact-free story true? We want to believe.