A son of the Theban king, Polydorus, the son of Cadmus, by Nycteis, who was descended from a Spartan family. Labdacus lost his father at an early age, and was placed under the guardianship of Nycteus, and afterwards under that of Lycus, a brother of Nycteus. When Labdacus had grown up to manhood, Lycus surrendered the government to him; and on the death of Labdacus, which occurred soon after, Lycus again undertook the guardianship of his son Laius, the father of Oedipus. (Paus. ix. 5. § 2; Eurip. Herc. Fur. 27; Apollod. iii. 5. § 5; comp. NYCTEUS.)