John Roach (December 25, 1815—January 10, 1887) was an American industrialist who rose from humble origins as an Irish immigrant laborer to found the largest and most productive shipbuilding empire in the postbellum United States, John Roach & Sons.Roach emigrated to the United States at the age of sixteen in 1832, eventually finding employment at the Howell Works of James P. Allaire in New Jersey, where he learned the ironmolder's trade.