Jacopo Tiepolo (died 19 July 1249), also known as Giacomo Tiepolo, was Doge of Venice from 1229 to 1249. He had previously served as the first Venetian Duke of Crete, and two terms as podestà in Constantinople (1218-1220 and 1224-1227). During his first term, following the capture and mysterious end of Peter of Courtenay, Tiepolo acted as de facto ruler of the Latin Empire, negotiating treaties on behalf of the Empire with Egypt and the Seljuk Turks.
Probably born in the latter part of the twelfth century, Jacopo assumed the post of Duke of Crete (Italian: duca di Candia) around the year 1212. During his tenure, Venetian dominion over Crete was challenged considerably by the Greek locals, culminating eventually in its capture at the hands of Marco Sanudo. His success, however, was short-lived, as a Venetian fleet soon arrived, forcing him to evacuate the island.
Jacopo was elected Doge on 6 March 1229, his predecessor Pietro Ziani having abdicated the month before. At the election, a stalemate was reached between Jacopo and his rival Marino Dandolo, both of them having twenty votes each. This was rectified by drawing lots, leading to Tiepolo's victory. This is thought to have sparked the feud between the Dandolo, who were an old aristocratic family, and the Tiepolo, who were seen as nouveau-riches. In an attempt to prevent the recurrence of a split vote in future elections, the number of electors was increased from forty to forty-one. Prior to ascending the ducal throne, Tiepolo also had to sign a traditional promissione, seriously limiting his powers.
Despite Emperor Frederick II's cordial visit to Venice in 1232, relations between the Empire and the Republic deteriorated. Consequently, in 1239, Venice joined the Lombard League and fought against Ezzelino III da Romano, a powerful ally of the Emperor. In the subsequent fights the Doge's son, Pietro Tiepolo, was captured at the Battle of Cortenuova on 27 November 1237. He was later taken to the Emperor's castle at Trani and hanged, worsening relations further.