Mahantango Creek (also known as Mahantongo Creek) is a 2.1-mile-long (3.4 km) tributary of the Susquehanna River in Snyder and Juniata counties, Pennsylvania, in the United States. Its name comes from a Delaware Indian word meaning "where we had plenty to eat". The creek flows along the border between Snyder County and Juniata County.
Historically, numerous sawmills and gristmills have been built on the creek. The first inhabitants of the area arrived in the late 1700s. In the 1750's, Peter and Michael Shaffer had land grants along and near the mouth of Mahantango Creek. They were both farmers, Michael also had a lumber mill and a distillery.
The watershed of the creek has an area of 86.2 square miles (223 km2). Trout inhabit the tributaries of Mahantango Creek, but not the main stem. Smallmouth bass, however, may inhabit Mahantango Creek itself.
Mahantango Creek begins at the border between Perry Township, Snyder County, Chapman Township, Snyder County, and Susquehanna Township, Juniata County. The creek's headwaters are at the confluence of North Branch Mahantango Creek and West Branch Mahantango Creek, near Pennsylvania Route 104. It heads southeast for a short distance and then turns northeast. Shortly afterwards, it turns southeast again, passing by the community of Mahantango. The creek then turns nearly due-south and crosses under U.S. Route 11 and U.S. Route 15. Shortly afterwards, it reaches its confluence with the Susquehanna River.