Marcellus is a town in Onondaga County, New York, United States. The population was 6,210 at the 2010 census. The town was probably named after Marcus Claudius Marcellus, a Roman general, by a clerk interested in the Classics.
The Marcellus Formation is a vast geological layer of shale spanning Pennsylvania, West Virginia and parts of other states and Ontario, which is named for an outcropping in or near Marcellus.
The Town of Marcellus contains a village also named Marcellus. The town and village are southwest of Syracuse.
According to the United States Census Bureau, the town has a total area of 32.7 square miles (84.6 km2), of which, 32.5 square miles (84.3 km2) of it is land and 0.1 square miles (0.3 km2) of it (0.40%) is water.
US Route 20 is an east–west highway through the south part of the town. New York State Route 175 is an east–west highway and intersects New York State Route 174 at Marcellus village.
Marcellus is at the east end of the Finger Lakes District and is at the north end of Otisco Lake. High hills, deep valleys, lake and streams, make the town remarkably scenic.