Funen (Danish: Fyn, pronounced [ˈfyːˀn]), with a size of 2,984 km² (1152 sq. miles), is the third-largest island of Denmark following Zealand and Vendsyssel-Thy, and the 163rd largest island of the world. Funen is located in the central part of the country and has a population of 454,358 inhabitants (2010). The main city is Odense, connected to the sea by canal, though this canal is now seldom used. The city's shipyard Odense Steel Shipyard has been relocated outside of Odense proper.

Funen belongs administratively to Region of Southern Denmark. From 1970–2006, the island formed the biggest part of Funen County, which also included the islands of Langeland, Ærø and Tåsinge, as well as a number of smaller islands.

Funen is linked to Zealand, Denmark's largest island, by the Great Belt Bridge carrying both trains and cars. The Great Belt Bridge is in reality two bridges; a low bridge connecting Funen to the small island of Sprogø in the middle of the Great Belt and a long suspension bridge the rest of the way to Zealand. The suspension bridge was the second longest in the world at the time of opening. From Funen to Sprogø, trains use a separate bridge parallel to the low bridge and constructed in a similar way. A tunnel connects Sprogø with Zealand, forming the other half of the railway connection.