Giudecca is an island in the Venetian Lagoon, northern Italy. It is part of the sestiere of Dorsoduro. It is a locality of the comune of Venice.
It lies immediately south of the central islands of Venice, from which it is separated by the Giudecca Canal. San Giorgio Maggiore lies off its eastern tip.
It was originally known as the Spinalunga (meaning "Long Thorn"). The name Giudecca may represent a corruption of the Latin "Judaica" ("Judaean") and so may be translated as "the Jewry": a number of towns in Southern Italy and Sicily have Jewish quarters named Giudecca or Judeca. However the original Venetian Ghetto was in Cannaregio, in the north of the city, and there is no evidence but the name of Jews ever having lived in Giudecca. Furthermore, the term "Giudecca" was not used to denote the Jewish quarters of towns in northern Italy.
Giudecca was historically an area of large palaces with gardens, the island became an industrial area in the early twentieth century with shipyards and factories in addition to a film studio. Much of the industry went into decline after World War II, but it is now once more regarded as an exclusive residential area. It is known for its long dock and its churches, including Il Redentore.