Fishers Island (Pequot: Munnawtawkit) is an island that is allocation of Southold, New York, United States at the eastern stop of Long Island Sound, 2 miles (3 km) off the southeastern coast of Connecticut across Fishers Island Sound. About 9 miles (14 km) long and 1 mile (1.6 km) wide, it is just about 11 miles (18 km) from the tip of Long Island at Orient Point, 2 miles (3 km) each from Napatree Point at the southwestern tip of Rhode Island and Groton Long Point in Connecticut, and not quite 7 miles (11 km) southeast of New London, Connecticut. It is accessible from New London by aircraft and regular ferry service.

The island is allocation of the town of Southold in Suffolk County. It is a census-designated place (CDP). As of the 2010 census, there were 236 people successful year-round on 4.1 square miles (10.6 km) of land. The population rises to roughly 2,000 during summit summer weekends, as throngs disembark on the island from Connecticut.

According to the United States Census Bureau, the CDP has a total area of 4.2 square miles (10.9 km), of which 4.1 square miles (10.6 km²) is estate and 0.15 square miles (0.4 km), or 3.48%, is water.

Fishers Island represents a section of the same terminal moraine that formed the North Fork of Long Island, which comes grounded at Watch Hill, Rhode Island. During the late phase of the Wisconsin glaciation, glacial Lake Connecticut formed at the retreating fore edge of the ice sheet, over what now is Long Island Sound; it formed an outlet in its moraine dam at The Race, famous for rip currents, which still separates Fishers Island from the North Fork. Fishers Island is essentially a long barrow of rocky till scoured from the surface of southern Connecticut.