Greek Empire most commonly refers to one of the following two empires: Macedonian Empire of Alexander the Great Byzantine Empire
It may also refer to one of the following Ancient Greek or Hellenistic entities:
Athenian Empire Spartan hegemony Theban hegemony Macedonian hegemony under Philip II Ptolemaic Empire Seleucid Empire Antigonid empire Lysimachian Empire Pyrrhic Empire Greco-Bactrian kingdom Indo-Greek kingdom Kingdom of Pontus under Mithridates VI
It may also refer to one of the following Byzantine entities:
Empire of Nicaea Despotate of Epirus Empire of Thessalonica Empire of Trebizond
See also Archaic Greece Magna Graecia Classical Greece Hellenistic armies