Seneca is a census-designated place (CDP) in Venango County, Pennsylvania, United States.

[3] According to the United States Census Bureau, the CDP has a total area of 2.2 square miles (5.7 km2), all of it land.

At the 2020 census,[5] there were 1010 people, 426 households and 300 families residing in the CDP.

There were 432 housing units at an average density of 192.6 per square mile (74.4/km2).

25.7% of all households were made up of individuals, and 13.5% had someone living alone who was 65 years of age or older.