In Greek mythology, Phorcys, or Phorkys was a primeval sea god, son of Pontus and Gaia and a brother of Thaumas, Nereus, Eurybia, and Ceto (Hes. Theog. 237; Apollod. i. 2. § 6).

According to the Homeric poems, an old man ruling over the sea, or "the old man of the sea," to whom a harbour in Ithaca was dedicated. He is described as the father of the nymph Thoosa (Odyssey i. 71, xiii. 96, 345).

By his sister Ceto he became the father of the Graeae and Gorgones (Hes. Theog. 270, &c.), the Hesperian dragon (ibid. 333, &c.), and the Hesperides (Schol. ad Apollon. Rhod. iv. 1399); and by Hecate or Cratais, he was the father of Scylla. (Schol. ad Apollon. Rhod. iv. 828; Eustath. ad Hom. p. 1714; Tzetz. ad Lycoph. 45.) Servius (ad Aen. v. 824) calls him a son of Neptune and Thoosa. (Comp. Muncker, ad Hygin. Fab. praef. p. 4.)

Phorcydes or Phorkides or Phorcynides, that is, the daughters of Phorcus and Ceto, or the Gorgons and Graeae. (Aeschyl. Prom. 794; Ov. Met. iv. 742, 774, v. 230 ; Hygin. Fab. Praef. p. 9.)