Kaser is a village in the town of Ramapo, Rockland County, New York, United States. The village is completely surrounded by the hamlet of Monsey. As of the 2020 United States census, the village population was 5,491. The village is the most densely populated municipality in New York State according to the 2010 census, being the only incorporated place in the state with a higher population density than New York City; and the 5th most in the United States.