King of Bithynia from c. 94 BCE to 74 BCE, upon his death, he left his kingdom to Rome.
Nicomedes IV succeeded his father, Nicomedes III, in 94 BCE. He was called the Euergetes, "the benefactor," for bringing prosperity to the needy. In 91 BCE, Mithridates expelled him from Bithynia and replaced him with Socrates, his brother. In 90 BCE, through the urging of the Roman orator, Quintus Horetensius Horatalus, the Roman Senate sent Manius Aquillius to restore Nicomedes to the throne. The Romans continued to support him as he invaded Mithridates' kingdom of Pontus in order to pay money to the Roman generals and ambassadors, who had helped him to overthrow his brother. During the First Mithridatic War, which soon followed as the Romans support Nicomedes' actions, Nicomedes continued to support the Romans. After a defeat near the river Amneius in 84 BCE, a Roman named Curio restored him once more to the throne.
In 81 BCE, the young
Gaius Julius Caesar rather famously visited the court of Nicomedes as a Roman ambassador. Caesar had been sent to raise a fleet; however, he took so long that rumors began to spread that he was having an affair with Nicomedes. This event led to him being referred to as the "Queen of Bithynia."
In 74 BCE, Nicomedes died, leaving his kingdom to Rome in his will, and Bithynia quickly became a new province of Rome. Mithridates IV, however, moved to incorporate it into his kingdom thus leading to the Third Mithridatic War.