Actress Michelle Gomez thinks that Missy could return to Doctor Who and face Jodie Whittaker's Doctor. The upcoming 11th season of Doctor Who has had a number of shakeups. A new showrunner, new female Doctor, and new group of companions means that the new season could be totally unexpected and wildly different from anything that came before.
Not only have Peter Capaldi and companion actors Pearl Mackie and Matt Lucas left the show but so has Gomez. She played Missy for the last three years, just as long as Capaldi has played The Doctor. The female incarnation of longtime nemesis The Master, Missy has been a constant thorn in The Doctor's side as well as one of his dearest friends. Until she was killed by her younger self in the 10th season finale. However, Gomez is not sure she is done with the beloved series. In fact, she's previously stated that she's open to returning to Doctor Who.
In an interview with Doctor Who Magazine, Gomez made it very clear that she believes Missy will be back someday. Gomez was adamant that the character has left a huge impression on her, and also that she has had a hard time saying goodbye to Missy.
"I think it's going to be really hard to shake this one off. Missy has made quite a big impression on me, and hopefully on the fans as well. She was such a great fit. Even though, for now, she has been laid to rest. I don't think she's ever going to be that far away. I loved playing this character so much, and it was really hard to see her go. But I think that in many different shapes and forms, she will be back. I can't really say much more than that. I have never had this response to anything else that I've done, and I'm really grateful for that."
Missy may have been killed by her previous incarnation, played by John Simm, who prevented her from regenerating in order to stop himself from ever becoming the Doctor's ally. But death does have a way of not being forever on the series. Missy faked her own death before, and Simm's version of The Master also died without regenerating, only to be resurrected. Not to mention that time travel is one of the main elements of the series, so even if Missy really is dead it's very possible for The Doctor to run into another version of her from earlier in her life. It's not uncommon for The Doctor to meet people out of order; he and his wife River Song practically lived their lives in opposite directions with him first meeting her on the day she died.
The Master/Missy is a popular character and it does seem likely that he or she will return in some form some day. Whether that would specifically be as Missy or a future incarnation is unknown at this time, especially since her return would have to be worked around Gomez's schedule on The Chilling Adventures of Sabrina. Still, the idea of the first female Doctor facing off against the first female Master, or Mistress, is enticing. After all, on Doctor Who, anything is possible.
Doctor Who season 11 premieres in October 2018 on BBC and BBC America.