Mistress is an intelligent talking horse, or Houyhnhnm, in Gulliver's Travels. The apparent leader of the Houyhnhms, Mistress finds Gulliver and befriends him. She adapts to Gulliver's speech more rapidly than he does hers. He struggles to prove to her and the others that he is not a savage Yahoo, but ultimately fails. However, Mistress is ultimately impressed that he is more Houynhnm than Yahoo, and assists him in leaving
In Jonathan Swift's original text, the Houyhnhnm who most assists Gulliver is male, referred to as "my Master."