Aristides J. Welch (September 28, 1811 – April 9, 1890) was an American Thoroughbred racehorse breeder. Welch owned Erdenheim Stud Farm at Chestnut Hill, Pennsylvania. In 1870 he purchased the mare from Captain T. G. Moore and stood her at Erdenheim. In 1872 he purchased the sire Leamington. Welch's broodmare selections led to Leamington becoming the Leading sire in North America in 1875, 1877, 1879, and 1881. Among those bred to Leamington was Maggie B. B. who produced three Classic winners in all, two of which were sired by Leamington. Their first was the 1879 Preakness Stakes winner, Harold, and their second was Iroquois, who in 1881 became the first American-bred horse to ever win England's famous Epsom Derby. Maggie B. B.'s third Classic winner was the colt by Welch's stallion, . Pa