Doctor Who: EVERY Version Of The Master Explained
4. Missy (First Appearance: 2014)
Missy is a hugely important incarnation of the Master, for two reasons.
By casting Michelle Gomez as a gender-flipped Master, Steven Moffat laid the groundwork for the first female Doctor a few years later. And as it pertains to the world of the show, Missy is the first incarnation since Roger Delgado who isn't an outright villain.
Perhaps reflecting Peter Capaldi's love of the Jon Pertwee era, Steven Moffat writes the Twelfth Doctor and Missy as two estranged friends. It's more heightened than Pertwee and Delgado because of Michelle Gomez's murderous Mary Poppins characterisation, but the friendship is still there, and it's stronger than ever.
Missy also builds on story elements introduced by the Shalka, Yana, and Saxon Masters. She's more of a companion than a villain, gets to pilot the TARDIS, she plays at being "Doctor Who," and she even tries to save the day.
Indeed, Missy's redemption arc was at the core of her character. She goes from raising a Cybermen army in the Series 8 finale, to choosing to stand with the Doctor against the Cybermen in the Series 10 finale.
However, the genuine tragedy of Missy is that the Doctor never sees her redemption, and never learns of her decision to stand with him. Before she can tell him, she's gunned down by the Saxon Master, setting up a cruel reset of the Doctor-Master relationship by the time of their next meeting.