Catonsville is a census-designated place (CDP) in Baltimore County, Maryland, United States. The population was 41,567 at the 2010 census. The community lies to the west of Baltimore along the city's border. Catonsville is the home of the University of Maryland, Baltimore County (UMBC), a public research university with over 12,000 students.

Europeans were the second group to settle the area now known as Catonsville. It is generally believed by historians that native tribes, known as the Piscataway, established villages here before the European colonists arrived. This tribe occupied the land between the Potomac River and Chesapeake Bay and up the Patapsco River. Catonsville was located along the Piscataway Trail. The colonists and the tribes got along until the mid-17th century, when the English government ended the practices of Catholic missionaries in the area. It is believed that the tribes were driven from their villages and some were hunted by slave catchers. As happened in many areas of early colonial America, diseases unknown to the tribes were spread by the colonists. Eventually, the tribes moved north under the protection of the Iroquois.