Mithridates or Mithradates VI Eupator was the ruler of the Kingdom of Pontus in northern Anatolia from 120 to 63 BC, and one of the Roman Republic's most formidable and determined opponents. He was an effective, ambitious and ruthless ruler who sought to dominate Asia Minor and the Black Sea region, waging several hard-fought but ultimately unsuccessful wars to break Roman dominion over Asia and the Hellenic world. He has been called the greatest ruler of the Kingdom of Pontus. He cultivated an immunity to poisons by regularly ingesting sub-lethal doses; this practice, now called mithridatism, is named after him. After his death, he became known as Mithridates the Great.

Pontus was a Hellenistic kingdom centered in the historical region of Pontus in modern-day Turkey, and ruled by the Mithridatic dynasty of Persian origin, which possibly may have been directly related to Darius the Great of the Achaemenid dynasty. The kingdom was proclaimed by Mithridates I in 281 BC and lasted until its conquest by the Roman Republic in 63 BC. The Kingdom of Pontus reached its largest extent under Mithridates VI the Great, who conquered Colchis, Cappadocia, Bithynia, the Greek colonies of the Tauric Chersonesos, and for a brief time the Roman province of Asia. After a long struggle with Rome in the Mithridatic Wars, Pontus was defeated.