The Bebryces were a tribe of people who lived in Bithynia. According to Strabo they were one of the many Thracian tribes that had crossed from Europe into Asia.
According to legend they were defeated by Heracles or the Dioscuri, who killed their king, Mygdon or Amycus. Their land was then given to King Lycus of the Mariandynians, who built the city Heraclea there. Some say Amycus was a brother of Mygdon and another Bebrycian king; both were sons of Poseidon and Melia. Greek mythology offers two different accounts for the origin of the name 'Bebryces': either from a woman named Bebryce (Eustath. ad Dionys. Perieg. 805.), or from a hero named Bebryx (or Bebrycus) (Steph. Byz. s.v. Bebrycus). Bebryce is possibly the same as Bryce, a daughter of Danaus, a mythical King of Libya and Arabia (Apollodorus). Bebryx was also the father of Pyrene.