Who is Missy, and what is her connection to the Master and the Doctor?

Missy is a character from the British science fiction television series Doctor Who. She is a Time Lady, like the Doctor, and is also known as the Mistress or the Master's female incarnation. She first appears in the eighth series of the show, played by Michelle Gomez.

Missy's connection to the Doctor and the Master is complex and often ambiguous. She claims to be the Master's future incarnation, but her true identity and motives are not revealed until later in the series. It is eventually revealed that she is a renegade Time Lady who has been manipulating events throughout history to bring the Doctor and the Master together.

Missy is known for her unpredictable and often deranged behavior, and is sometimes an ally of the Doctor and sometimes an enemy. She is a fan favorite character who brings a unique energy and wit to the show.