Hartly is a town in Kent County, Delaware, United States. It is part of the Dover, Delaware Metropolitan Statistical Area. The population was 74 at the 2010 census, making it the least populous municipality in Delaware.
Hartly is located at 39°10′07″N 75°42′46″W / 39.168485°N 75.712712°W / 39.168485; -75.712712.
According to the United States Census Bureau, the town has a total area of 0.1 square miles (0.2 km²), all of it land.