Plessis is a hamlet and census-designated place in the town of Alexandria in Jefferson County, New York, United States.

[3] Plessis had a post office from September 16, 1823, until March 26, 2011; it still has its own ZIP code, 13675.

[4][5] New York State Route 26 passes through the community.

According to the U.S. Census Bureau, the community has an area of 0.346 square miles (0.90 km2), all land.

This article about a location in Jefferson County, New York is a stub.