Along with Twelfth Doctor Peter Capaldi and showrunner Steven Moffat, Michelle Gomez was previously confirmed to be leaving Doctor Who after season 10. As a result, the recent finale episode saw Missy murdered by her past regeneration (the wonderful John Simm) and apparently, the blast was so powerful that the character wouldn't even be able to regenerate and was presumably left to die for good.
However, it seems that fans may not have seen the last of Michelle Gomez in Doctor Who just yet. Asked at this year's San Diego Comic Con (via Radio Times) about a potential return, Gomez replied:
"It's good to know when to leave the party. It was a jolly good party, but time to leave - and then maybe come back - but time to leave for now... It feels like this was a chapter – a perfect chapter, actually – with Steven [Moffat] and Peter [Capaldi]. I don't know about being a Master to another Doctor. I feel very loyal to Peter and I don't know how that would work, but I am willing to find out at a later date."
Clearly then, fans shouldn't expect to see Missy in Doctor Who's near future - perhaps not even for Jodie Whittaker's entire run - but a return in the long time is very much a possibility. John Simm recently proved that there's certainly opportunities for previous Master regenerations to come back to the show and wreak some havoc and as anyone familiar with the Master's history will know, it'll take more than a deadly laser beam to keep the evil Time Lord down permanently.
Of course, with John Simm's recent reprisal of the role, it may seem somewhat repetitive if Missy were to pull the same trick, even if it didn't happen for a number of years. The more characters from the show's past are brought back, the less emotional impact it has on the audience, as viewers come to expect returns and the element of surprise is lessened.
With that said, Gomez made a wonderful villain on Doctor Who and it could be argued that her character arc was left somewhat unfinished. Although Missy eventually made the decision to side with The Doctor, the hero himself was completely unaware of this and it would be immensely satisfying for fans to see Gomez's character return and let The Doctor know that he did indeed help to change her ways.
Doctor Who season 11 is expected to premiere in 2018 on BBC.
Source: Radio Times