The Kingdom of Pergamon, Pergamene Kingdom, or Attalid kingdom was a Greek state during the Hellenistic period that ruled much of the Western part of Asia Minor (now Turkey) from its capital city of Pergamon. It was ruled by the Attalid dynasty (/ˈætəlɪd/; Greek: Δυναστεία των Ατταλιδών, romanized: Dynasteía ton Attalidón).
The kingdom was a rump state that was created from the territory ruled by Lysimachus, a general of Alexander the Great. Philetaerus, one of Lysimachus' lieutenants, rebelled and took the city of Pergamon and its environs with him; Lysimachus died soon after in 281 BC. The new kingdom was initially in a vassal-like relationship of nominal fealty to the Seleucid Empire, but exercised considerable autonomy and soon became entirely independent. It was a monarchy ruled by Philetaerus's extended family and their descendants. It lasted around 150 years before being eventually absorbed by the Roman Republic during the period from 133–129 BC.