Dennis is a town in Barnstable County, Massachusetts, United States; located near the center of Cape Cod. The population was 14,207 at the 2010 census.
The town encompasses five distinct villages, each of which has its own post office. These constituent villages are Dennis (including North Dennis), Dennis Port, East Dennis, South Dennis, and West Dennis.
Dennis was first settled in 1639, by John Crowe (later Crowell) and Thomas Howes, as part of the town of Yarmouth. The town officially separated and incorporated in 1793. It was named after resident minister, Josiah Dennis. There was not enough land for farming, so seafaring became the town's major industry in its early history, centered around the Shiverick Shipyard.