In a recent interview, she said: “It’s definitely not something I’ve ruled out.
“It was a couple of years ago I was on Doctor Who but I do still feel really close to Bill and I do feel like she’s still very much part of me.
“And I feel like I’d sort of have to miss her before going back to her again, or if there was an amazing story that was written about her and her experiences and meeting another Doctor
“But it’s such a great show and I would be crazy to say no,” she told RadioTimes.com.
Doctor Who returns to BBC One later in the year.