Cotys III, also known in dynastic terms as Cotys VIII (Ancient Greek: Κότυς, flourished second half of 1st century BC & first half of 1st century, died 19) was the Sapaean Roman client king of eastern Thrace from 12 to 19.
Cotys was the son and heir of loyal Roman client rulers Rhoemetalces I and Pythodoris I of Thrace. Cotys’ mother is only known through surviving numismatic evidence, which bears her image and her Royal title of Queen Pythodoris.
Cotys’ father Rhoemetalces I was a loyal ally to the first Roman Emperor Augustus. Rhoemetalces I was a direct descendant of the Thracian King Cotys I. Rhoemetalces I was the son of a previous Thracian King, whose name was Cotys and his mother is unknown. Rhoemetalces I was the middle son, who had an elder brother who was called Cotys and his younger brother was Rhescuporis II.
Rhoemetalces I’s eldest brother Cotys who was Thracian King and an ally to Roman General Pompey and sent Pompey a body of auxiliaries under his son Rhescuporis I in 48 BC, in the Roman civil war against Gaius Julius Caesar. When Rhoemetalces I’s brother died, his nephew Rhescuporis I, became Thracian King. Rhoemetalces I’s became the guardian to the child and son of his brother Cotys. Rhescuporis I died in 13 BC, when he was defeated and slain in battle by the Vologaeses Chief of the Thracian Bessi, who was a leader in the revolt against the Romans in that year.
During this revolt Rhoemetalces I and his family had fled Thrace and return when the revolt had ended. Augustus then returned Thrace to him and his family. When Rhescuporis I died, Rhescuporis I left no heir and Rhoemetalces I became King of Thrace in 12 BC. Rhoemetalces I ruled Thrace until his death in 12. The Roman Historian Tacitus, describes Rhoemetalces I as ‘attractive and civilized’.
When Rhoemetalces I died Augustus had divided the kingdom into two separate kingdom: one part for his son Cotys to rule and other half for Rhoemetalces I’s remaining brother Rhescuporis II to rule. Tacitus states that Cotys received the cultivated parts, most towns and most Greek cities of Thrace, while Rhescuporis received the wild and savage portion with enemies on its frontier.