Pheasant Island (German: Fasaneninsel) is one of the two islands in the south of the lake of Großer Eutiner See, which itself lies in the borough of Eutin in the district of Ostholstein in the German state of Schleswig-Holstein. The island is about 150 m × 200 m (490 ft × 660 ft) across.
From the 9th century, Pheasant Island was the site of a Wendish castle which was given the name Utin and was the centre of the eponymous Gau. The castle was linked to the shore over a bridge.
The castle was destroyed in 1138/39 by the Holsteiners during the conquest of Wagria. The subsequent settlement was built on the shore and developed into the present-day town of Eutin.