Eupator of Bithynia was a king who ruled the ancient kingdom of Bithynia in northwestern Anatolia during the late 2nd century BCE. He is known for his efforts to strengthen his kingdom and for his interactions with neighboring states, including Pontus and Rome. His reign was marked by political maneuvering and alliances. Eupator was the son of King Nicomedes I and succeeded him on the throne. His rule faced challenges, including conflicts with Mithridates VI of Pontus, which ultimately led to significant changes in the region's power dynamics. His legacy is tied to the history of Bithynia and its eventual incorporation into the Roman Empire.