This is a list of known military alliances of ancient Greek poleis. They comprise the terms symmachia and koinon, both of which meant a league for the mutually supportive conduct of war, both offensive and defensive. The terms might be used with the same referents in the same source or be used mutually exclusively in the sources. Both words had other meanings, which are not covered here.

In theory at the time the poleis were meant to be autonomous. In fact the autonomy varied a great deal, which everyone of the times knew. Complaints and revolts were common. Apart from the domination of large states, such as Athens and Sparta, the leagues were named after the ethnic regions they were intended to defend. They were an intermediate step between the independent poleis and the Macedonian, Roman, or Persian provincial administrations that brought the poleis to an end and replaced the politeia with a local government subordinate to a province. "Federation," "confederacy," and a third term, sympoliteia only describe the degree of independence, or lack of it. Different scholars respect a wide degree of latitude.

Not yet tabularized
 Phocian League (Κοινὸν τῶν Φωκέων, Koinon ton Phokeon), existing 6th century BC to 196 BC, 189 to 146 BC and 21 BC to 297 AD
 Thessalian League (Κοινὸν τῶν Θεσσάλων, Koinon ton Thessalon), existing 6th century to 146 BC
 League of the Magnetes (Κοινὸν τῶν Μαγνητῶν, Koinon ton Magneton), existing 197 BC to 297 AD
 Aenianian League (Κοινὸν τῶν Αἰνάνων, Koinon ton Ainianon) existing 168 to 21 BC
 Arcadian League (Koinon ton Arkadon) existing 370 to c. 230 BC
 League of the Oeteans (Κοινὸν τῶν Οἰταίων, Koinon ton Oitaion) existing 167 to 21 BC
 Euboean League (Κοινὸν τῶν Εὐβοιέων, Koinon ton Euboieon) existing from  c. 290 BC to 297 AD
 Epirote League (Κοινὸν τῶν Ἠπειρωτῶν Koinon ton Epiroton), existing from c. 320 to c. 170 BC
 Boeotian League (Κοινὸν τῶν Βοιωτῶν Koinon ton Boioton), existing from  c. 550 to 171 BC and 21 BC to 297 AD
 League of the Islanders (Κοινὸν τῶν Νησιωτῶν, Koinon ton Nesioton), existing from c. 314 to c. 220 BC and 200 to 168 BC
 Cretan League existing 69 BC to 4th century AD
 Koinon of Macedonians existing 168 BC to 297 AD
 Lycian League, founded in 168 BC, lasted until 43 AD
 League of Free Laconians, a league of cities in Laconia re-established by Roman emperor Augustus in 21 BC
 Aetolian League (Κοινὸν τῶν Αἰτώλων, Koinon ton Aitolon), early 3rd century to 146 BC
 Achaean League (Κοινὸν τῶν Ἀχαιῶν, Koinon ton Achaion), 280 BC to 146 BC, dissolved by the Romans after the Battle of Corinth (146 BC)
 Koinon galaton, the Galatian League in Asia Minor
 Koinon of the Zagorisians under the Ottoman Empire, 1670–1868
 The Delian League

The Athenian Empire, also known as the Delian League, was a collection of Greek city-states largely based around the Aegean Sea which operated under the hegemony of Athens. This alliance initially served the purpose of coordinating a united Greek front against a perceived looming Persian threat against the Ionian city-states which bordered it. The members of the Delian League were made to swear an oath of loyalty to the league and contributed mostly monetarily but in some instances donated ships or other forces. It was also the case that many democratic members of the League owed their freedom from oligarchic or tyrannical rule to Athens. Because of this, Athens gained an overwhelming advantage in the voting system conducted by relying on the support of democratic city-states Athens had helped into being. By 454 Athens moved the treasury of the Delian League from the Island of Delos to the Parthenon in Athens. Benefitting greatly from the influx of cash coming out of the 150-330 members, Athens used the money to reinforce its own naval supremacy and used the remaining funds to embellish the city with art and architecture. In order to maintain the new synoecism, Athens began using its greatly expanded military to enforce membership in the League. City-states who wished to leave the alliance were punished by Athens with force such as Mytilene and Melos. No longer considered her allies, Athens eventually began to refer to the members of the Delian League as "all the cities Athens rules." Athens also extended its authority over members of the League through judicial decisions. Synoecism under the Athenian Empire was enforced by resolving matters of and between states in Athens by courts composed of Athenian citizens and enforcing those decisions through the Athenian military.
 Peloponnesian League
 League of Corinth
 Achaean League
 Aetolian League
 Epirote League
 League of the Islanders
 Amphictyonic league
 Arcadian League
 Chrysaorian League

References

leagues
Military history of Greece
leagues