Iroquoian-speaking North American Indian tribe that traditionally lived in palisaded towns along the Susquehanna River in what are now New York, Pennsylvania, and Maryland. Little is known of Susquehannock political organization, but they are thought to have been subdivided into several subtribes and clans; the name may have referred originally to a confederacy of tribes. Like other Iroquoian tribes, they were semisedentary agriculturalists.

The Susquehannock were first described by Capt. John Smith, who explored the upper Chesapeake Bay area in 1608. Throughout the historical period they were at war with the Iroquois, who conquered them in 1676 and forced them to settle near the Oneida tribe in New York. They were later allowed to return to their former territory along the Susquehanna River. Epidemics steadily reduced their number (estimated to have been about 5,000 in 1600), and in 1763 many of the remaining Susquehannock were massacred by whites inflamed by accounts of an Indian war on the Pennsylvania frontier, several hundred miles away. Susquehannock descendants numbered more than 400 in the early 21st century.