Collier Township is a township in Allegheny County, Pennsylvania, United States. The population was 8,931 at the 2020 census, an increase over the figure of 7,080 tabulated in 2010.

Rennerdale is an unincorporated community and census-designated place in Collier Township, Allegheny County, Pennsylvania, United States, about 9 miles (14 km) southwest of Pittsburgh. As of the 2020 census it had a population of 1,103.