Hamlin Township is a township in McKean County, Pennsylvania, United States. The population was 819 at the 2000 census.According to the United States Census Bureau, the township has a total area of 167.3 km. 167.2 km of it is land and 0.1 km of it is water.As of the census of 2000, there were 819 people, 349 households, and 241 families residing in the township. The population density was 4.9/km. There were 617 housing units at an average density of 3.7/km. The racial makeup of the township was 99.63% White, 0.24% Asian, and 0.12% from two or more races. Hispanic or Latino of any race were 0.24% of the population.There were 349 households, out of which 26.9% had children under the age of 18 living with them, 56.7% were married couples living together, 8.6% had a female householder with no husband present, and 30.9% were non-families. 26.1% of all households were made up of individuals, and 9.7% had someone living alone who was 65 years of age or older. The average household size was 2.