Trojan prince in Greek mythology, son of King Priam and Queen Hecuba of Troy. It had been prophesied that Troy would never fall if Troilus reached the age of 20. When Troilus was a boy, Achilles ambushed him as he was drinking from a fountain and killed him. His sister, Polyxena, eventually also died on account of Achilles.

In medieval handlings of the Trojan story Troilus was portrayed as the embodiment of an innocent young lover betrayed by a fickle girl who abandoned him for the Greek hero Diomedes. This story of Troilus's unhappy passion appears to have been invented early in the 12th century by Benoît de Sainte-Maure in the poem Roman de Troie. Benoît called the girl Briseida, a name later modified by other writers to Cressida. The 14th century saw two important treatments of the Troilus and Cressida theme: Giovanni Boccaccio's poem Il filostrato (derived from Benoît and from the Historia destructionis Troiae of Guido delle Colonne) and Geoffrey Chaucer's Troilus and Criseyde (based mainly on Boccaccio). Their story was also the subject of Shakespeare's play Troilus and Cressida.