William Cathcart was born in Scotland in about 1710. Cathcart moved to North Carolina in 1737, initially residing in Bertie County. A merchant, he also worked as a physician and resided on a plantation in Northampton County, North Carolina. Cathcart served as a local justice of the peace and sheriff and also managed his plantation, which was home to several enslaved people. Cathcart held a correspondence with Samuel Johnston, his son-in-law, about the management of their estates and enslaved people. Cathcart died in Northampton on February 27, 1773.