In Greek mythology, Polydorus or Polydoros (Ancient Greek: Πολύδωρος, "many-gifted") was the youngest son of Priam of Troy. Homer makes his mother Laothoe and has Achilles spear him on the battlefield; later tragedy and epic — Euripides' Hecuba, Ovid, Virgil — send him for safety to Thrace, where King Polymestor murders him for Priam's gold. Distinct from Polydorus son of Cadmus and from other namesakes.
Adapted from Wikipedia, "Polydorus (son of Priam)" · CC BY-SA 4.0
I.In the Iliad
Homer presents Polydorus only briefly: Priam's youngest and dearest son, forbidden to fight, yet showing off his speed among the ranks until Achilles spears him. Hector, seeing his brother fall, is driven to face Achilles.
II.Hecuba, Ovid, and the Aeneid
In Euripides' Hecuba the ghost of Polydorus speaks the prologue: Priam had sent him with gold to Polymestor of Thrace against Troy's fall; once the city fell, Polymestor killed the boy and stole the treasure, casting the body into the sea. Hecuba finds the corpse, blinds Polymestor, and kills his sons. Ovid retells the same Thracian murder in the Metamorphoses.
Virgil's Aeneid has Aeneas land in Thrace and uproot blood-spouting myrtle from a mound — the spears that slew Polydorus have taken root. The dead prince warns him away from the treacherous shore; Aeneas gives him proper burial.
III.Hyginus' variant
In Hyginus, Polydorus is raised by his sister Iliona, wife of Polymestor, swapped with her own son Deipylus so that Polymestor, bribed by the Greeks to kill Priam's child, murders the wrong boy. Learning the truth from Apollo's oracle and Iliona, Polydorus blinds and kills Polymestor.