Duncan Township is a township in Tioga County, Pennsylvania, United States. The population was 188 at the 2020 census.

Tioga County is a county in the Commonwealth of Pennsylvania. As of the 2020 census, the population was 41,045. Its county seat is Wellsboro. The county was created on March 26, 1804, from part of Lycoming County and later organized in 1812. It is named for the Tioga River. The county is part of the North Central Pennsylvania region of the state.