Troilus was the son of Priam (or Apollo) and Hecabe. His name can be read as either 'Trojan' or 'descendant of Tros'. The latter, of course, gave his name to Troy (see his name). Troilus' name is more familiar from Shakespeare's play Troilus and Cressida than it is from the brief references to him by classical writers such as Homer and Virgil.
