In Greek mythology, King Haemus (or Haimos) of Thrace was the son of Boreas. He was vain and haughty and compared himself and his wife, Rhodope, to Zeus and Hera. They changed him and his wife into mountains (Haemus Mons and Rhodope Mountains, respectively). In Greek, the Balkan Peninsula was thus known as the Peninsula of Haemus (Χερσόνησος του Αίμου). This naming of the Balkans has some basis amongst today greeks as well.

Greek mythological people | Thracian kings