The ancient Thracians; Ancient Greek: Θρᾷκες, Latin: Thraci) were a group of Indo-European tribes inhabiting a large area in Central and Southeastern Europe. They spoke the Thracian language – a scarcely attested branch of the Indo-European language family. The study of Thracians and Thracian culture is known as Thracology.

The first historical record about the Thracians is found in the Iliad, where they are described as allies of the Trojans in the Trojan War against the Greeks. The ethnonym Thracian comes from Ancient Greek Θρᾷξ (plural Θρᾷκες; Thrax, Thrakes) or Θρᾴκιος/Ionic: Θρηίκιος (Thrakios/Thrēikios), and the toponym Thrace comes from Θρᾴκη/Ion.: Θρῄκη (Thrakē/Threkē). Both names are exonyms developed by the Greeks.

In Greek mythology, Thrax (by his name simply the quintessential Thracian) was regarded as one of the reputed sons of the god Ares. In the Alcestis, Euripides mentions that one of the names of Ares himself was Thrax since he was regarded as the patron of Thrace (his golden or gilded shield was kept in his temple at Bistonia in Thrace).