The Duchy of Athens was one of the Crusader States set up in Greece after the conquest of the Byzantine Empire during the Fourth Crusade.

The first duke of Athens (as well as Thebes, at first) was Otto de la Roche, a minor Burgundian knight of the Fourth Crusade. Although he was known as the "Duke of Athens" from the foundation of the duchy in 1205, the title did not become official until 1280.

Athens was originally a vassal state of the Kingdom of Thessalonica, but after Thessalonica was captured in 1224 by the Byzantine Despot of Epirus, the duchy became a vassal of the Principality of Achaea. The Duchy occupied the Attic peninsula and extended partially into Macedonia, sharing an undefined border with Thessalonica and then Epirus. It did not hold the islands of the Aegean Sea, which were Venetian territories. The buildings of the Acropolis in Athens served as the palace for the dukes.

The de la Roche family held the duchy until 1308 when Walter of Brienne became duke. Walter hired the Catalan Company, a group of mercenaries led by Roger de Flor, to fight for the Duchy against the Byzantine successor states of Epirus and Nicaea, but in 1311 they overthrew Walter and took over the Duchy, making Catalan the official language and replacing the French and Byzantine-derived laws Principality of Achaea with the laws of Catalonia. The Duchy was then ruled by the kings of Aragon and Sicily (who were lords of Catalonia) until 1388 when the Acciajuoli family of Florence took control.

From 1395 to 1402 the Venetians briefly controlled the Duchy. In 1444 Athens became a tributary of Constantine Palaeologus, the despot of Morea and heir to the Byzantine throne. In 1456, after the Fall of Constantinople to the Ottoman Empire, Sultan Mehmed II conquered the remnants of the Duchy.

Dukes of Athens