For other uses, see Cressida (disambiguation).

Cressida (also Criseida, Cresseid or Criseyde) is a character who appears in many Medieval and Renaissance retellings of the story of the Trojan War. She is a Trojan woman, daughter of Calchas, who falls in love with one of the sons of King Priam, Troilus. She pledges everlasting love, but when she is sent to the Greeks as part of a hostage exchange, she forms a liaison with the Greek warrior Diomedes. The character's name is derived from that of Chryseis.

The story of Troilus and Cressida is a medieval invention and does not appear in any Greek legends. The best known versions are Geoffrey Chaucer's poem Troilus and Criseyde, Robert Henryson's poem The Testament of Cresseid and William Shakespeare's play Troilus and Cressida (c. 1603). In the original version of the story in the Roman de Troie the romance was attached to Briseida and this version influenced the poem of Azalais d'Altier. It is Boccaccio who makes the decisive shift in name in Il Filostrato

She has most often been depicted by writers as a paragon of female inconstancy. Chaucer's poem, however, portrayed a far more sympathetic Criseyde showing a self-conscious awareness of her literary status: "Alas, of me until the world's end shall be wrote no good song".

The character of Cressida has also appeared in more modern drama. In the 1965 Doctor Who storyline "The Myth Makers" (with William Hartnell as the Doctor), wildly inaccurate from a literary point of view, the TARDIS is captured by the Trojans with Vicki (Maureen O'Brien) still inside. Forced to emerge from the TARDIS, Vicki meets Priam, King of Troy. Considering the name 'Vicki' to be 'outlandish', Priam gives her the name of 'Cressida'. Later, Vicki/Cressida meets and becomes enamored with Priam's youngest son Troilus. After Troy falls (with the unwilling, but necessary help of the Doctor), Vicki stays behind to rebuild Troy with Troilus. The story deliberately inverts the traditional fates of Troilus and Cressida.