Willet is a town in Cortland County, New York, United States. The population was 1,043 at the 2010 census. The town is named after Colonel Marinus Willet. It is in the southeast corner of the county, southeast of Cortland.
Willet was within the former Central New York Military Tract. The area was first settled around 1797.
Willet was created from a part of the town of Cincinnatus in 1813. In 1865, the population was 982.