Medusa is a hamlet in the Town of Rensselaerville, in Albany County, New York, United States.

In 1850, the name of the village was changed to Medusa, at that time the village contained a Methodist Episcopal and a "Christian" Church, a hotel, two stores, two mills for grain, turning works, an evaporator, paper mill, carpenter's shop, and two Blacksmith's shops.

There were 183 housing units at an average density of 27.0 per square mile (10.4/km2).

The racial makeup of the CDP was 99.20% White, 0.27% Native American, 0.27% Asian, and 0.27% from two or more races.

21.8% of all households were made up of individuals, and 7.5% had someone living alone who was 65 years of age or older.