In Greek mythology, Deidamia (or Deidamea, Deidameia; Greek Δηιδάμεια) is the daughter of King Lycomedes of Scyros.
Deidamia was one of King Lycomedes's seven daughters with whom Achilles was concealed. Some versions of this story state that Achilles was hidden in Lycomedes's court as one of the king's daughters, some say as a lady-in-waiting under the name "Pyrrha". Despite the fact that Achilles and Deidamea could have been as young as eight years old, the two soon became romantically involved to the point of intimacy. After Odysseus arrived at Lycomedes's palace and exposed Achilles as a young man, Achilles decided to join the Trojan War, leaving behind a pregnant, heart-broken Deidamia. Their son, Neoptolemus, later joined his father in the Trojan War but was eventually killed by Orestes. It is also mentioned that Neoptolemus gave Deidamia in marriage to his ally Helenus. Ptolemy Hephaestion mentions that Achilles and Deidamia had another son, Oneiros, who was unwittingly killed by Orestes.