John Carroll, (January 8, 1735 – December 3, 1815) was a prelate of the Roman Catholic Church who served as the first bishop and Archbishop in the United States.arroll is also known as the founder of Georgetown University, (the oldest Roman Catholic university in the United States), and of St. John the Evangelist Parish of Rock Creek, (now Forest Glen), the first secular (diocesan) parish in the country. This means its clergy did not come from monastic orders.