Cotys I (Ancient Greek: Κότυς; died 48 BC) was a Sapaean client king of the Odrysian kingdom of Thrace from to . He was the son of Rhoemetalces.
Cotys was an ally of the Roman general Pompey, to whom he sent a body of auxiliaries under his son Rhescuporis I in 48 BC for use in the Roman civil war against Julius Caesar.
On Cotys' death, Rhescuporis I became king under the regency of Rhoemetalces I, Cotys' younger brother.