Eumenes II of Pergamon (/juːˈmɛniːz/; Greek: Εὐμένης Βʹ; ruled 197–159 BC) was king of Pergamon and a member of the Attalid dynasty. The son of king Attalus I and queen Apollonis, he followed in his father's footsteps and collaborated with the Romans to oppose first Macedonian, then Seleucid expansion towards the Aegean, leading to the defeat of Antiochus the Great at the Battle of Magnesia in 190 BC.