Oark is an unincorporated community in Johnson County, Arkansas, United States. Oark is located on Arkansas Highway 215, 16 miles (26 km) northwest of Clarksville. Oark has a post office with ZIP Code 72852. The community is surrounded by the Ozark National Forest with the scenic Mulberry River nearby. The origin of the town’s name is unknown, although many believe it came from French trappers that frequented this isolated valley in the 18th century.