The Frankish Occupation (Medieval Greek: Φραγκοκρατία, romanized: Frankokratia; anglicized as 'Francocracy'), also known as the Latinokratia (Λατινοκρατία, Latinokratía) and, for the Venetian domains, Venetian Occupation (Βενετοκρατία / Ενετοκρατία, Venetokratía / Enetokratía), were the collection of primarily French and Italian states, fiefs and colonies that were established by the Partitio terrarum imperii Romaniae on the territory of the partitioned Byzantine Empire following the Sack of Constantinople of 1204 during the Fourth crusade.

The terms Frankokratia and Latinokratia derive from the name given by the Orthodox Greeks to the Western French and Italians who originated from territories that once belonged to the Frankish Empire, as this was the political entity that ruled much of the former Western Roman Empire after the collapse of Roman authority and power. The span of the Frankokratia period differs by region: the political situation proved highly volatile, as the Frankish states fragmented and changed hands, and the Greek successor states re-conquered many areas.

With the exception of the Ionian Islands and some islands or forts that remained in Venetian hands until the turn of the 19th century, the, in some cases temporary, end of the Frankokratia in most Greek lands came with the Ottoman conquest, chiefly in the 14th to 17th centuries.

The Latin Empire (1204–1261), centered in Constantinople and encompassing Thrace and Bithynia, was created as the successor of the Byzantine Empire after the Fourth Crusade, while also exercising nominal suzerainty over the other Crusader principalities. Its territories were gradually reduced to little more than the capital, which was eventually captured by the Empire of Nicaea under the rule of Michael VIII Palaiologos in 1261.

Genoese attempts to occupy Corfu and Crete in the aftermath of the Fourth Crusade were thwarted by the Venetians. It was only during the 14th century, exploiting the terminal decline of the Byzantine Empire under the Palaiologos dynasty, and often in agreement with the weakened Byzantine rulers, that various Genoese nobles established domains in the northeastern Aegean:

The Republic of Venice accumulated several possessions in Greece, which formed part of its Stato da Màr. Some of them survived until the fall of the Republic itself in 1797:

The fragmentation of the Byzantine Empire caused communication problems and gradually led to the division of koiné into dialects. The prestige of the literary language also declined, because the Franks used the language of the common people for administration purposes in the conquered areas. Latin loanwords flooded the language, mostly Italian, including dialects, such as Venetian. Next in frequency are French words, followed by a very small number of words from Provençal, Catalan, Spanish, etc. The vocabulary of feudal law and property ownership was mainly French, while the vocabulary of trade and shipping was Italian.

Linguistic interaction between Greeks and Franks appear in toponymy and, to a limited extent, in personal names. Frankish place names in Greece constitute the most significant linguistic influence exerted by the Franks: Μπελβεντέρε < Belvedere = Καλλιθέα, Καλοσκόπι. Μαλεβίζι < Malvezino = bad neighbor. The names Ανέζα (Agnes), Αμαλία (Amalie), Φλόρα (Flora), Μαργαρίτα (Margheritte), Λοΐζος (Loys), Στίνης (Estienne, Étienne) are of Frankish origin. Also, words such as amantizo αμαντίζω < amendrer = βελτιώνω, ασεντζίζω < assiger = πολιορκώ, ρόι, ρήγας < roy = βασιλιάς, ροΐνα, ρήγαινα < reine are of French origin. Many Latin words, mainly military terms and terms of feudal law, took root in the Greek language after phonetic changes and semantic specializations such as: φουσσάτο < fossatum castrum or πρίγκηπας < princeps. Latin can also be traced in given names: Ιερώνυμος, Βαλεντίνος, Γάσπαρης, Γερώνυμος, Λοΐζος, Μπατής, Πασχάλης και Φενδερίκος.