Bailo or baylo (plural baili or bayli) is a Venetian title that derives from the Latin term , meaning "porter, bearer". In English, it may be translated bailiff, or otherwise rendered as bailey, baili, bailie, bailli or baillie. The office of a bailo is a bailaggio (sometimes anglicised "bailate"). The term was transliterated into Greek as μπαΐουλος (baioulos), but Nicephorus Gregoras translated it ἐπίτροπος (epitropos) or ἔφορος (ephoros).
In the Middle Ages, a bailo was a resident ambassador of the Republic of Venice. The most famous baili were those at Constantinople, who were, from 1268, the Venetian ambassadors to the Byzantine court and, after 1453, to the Ottoman government. There were also permanent baili at Negroponte, Durazzo and Corfu. Baili were also sent to represent Venetian interests at the courts of Cyprus, Acre (Jerusalem), Armenia and Trebizond. In the mid-thirteenth century, the Venetian consuls in Tyre and Tripoli in the kingdom of Acre were upgraded to the rank of bailo. Venice also sent baili to oversee its colonies at Aleppo, Antivari, Koroni, Modon, Nauplia, Patras and Tenedos.