William Gregg (1800 – September 13, 1867) was an ardent advocate of industrialization in antebellum Southern United States. In 1847 he founded the successful Graniteville Company, a large scale Horse Creek Valley, South Carolinacotton mill.
Gregg publicized his ideas in his 1845 Essays on Domestic Industry. He argued that economic domination by the North was best met by Southern industrialization. He gained sufficient support for his own efforts, but was unable to bring about any general change in the agrarian southern economy.