The British actress, who is currently promoting Disney's live-action film "The Nutcracker and the Four Realms", made an appearance on "The Late Late Show with James Corden" on Tuesday night (October 16).
During the chat, host James Corden asked Keira if she is ever confused with other celebs, and she recalled a time when she was mixed-up with the popstar while in a shop in Los Angeles.
"It was a weird one," she said. "So, I had my picture as Britney Spears. I quite enjoy it. I'm much more polite, I think, when people think I'm somebody else."
Keira went on to explain that the person she most often gets mistaken for is Natalie Portman, which she understands is due to them both appearing in 1999 movie "Star Wars: Episode I - The Phantom Menace".
"I have been chased through an airport as Natalie Portman. I have had many pictures as Natalie Portman," the 33-year-old sighed. "I've been chased through a park as Kate Winslet. And quite a few people have come over to me to ask me to say hello to Daniel Craig for them, because they think I'm (his wife) Rachel Weisz - which is lovely."
Host James pointed out that he would get fed up with being mistaken for other celebrities, but fellow guest Kathryn Hahn insisted she enjoys it when she is confused with "Saturday Night Live" actress Ana Gasteyer.
"It's kind of bananas. She actually told me that when "Bad Moms" came out, she would go to Starbucks, she'd order something and they'd give her a cup that would just say 'Carla' - which was my character's name from Bad Moms," smiled Kathryn. "And people come up to me all the time and say, 'I love you on SNL.' And I say, 'Thank you'."