The Mistress

Mistress or the Mistress refers to several characters.

Missy
 * The Mistress, a character in AUDIO: The Choice and The Search.
 * The Mistress, a character in TV: Warriors of Kudlak.
 * (short for "the Mistress"), the female incarnation of the Master, who debuted in TV: Deep Breath.
 * "Mistress" was a general form of address used by various models of K9 toward female allies including Leela, Romana, and Sarah Jane Smith.