John Hare Powel (22 April 1786 in Philadelphia, Pennsylvania – 14 June 1856 in Newport, Rhode Island) was an American agriculturist, art collector and philanthropist.
He was born John Powel Hare, the youngest of the six children of Robert and Margaret Willing Hare. As a youth, he was adopted by his mother's widowed and childless sister, Elizabeth Willing Powel (1743–1830), and was educated at The Academy and College of Philadelphia. He legally changed his name when he attained his majority, and inherited the immense fortune of his late uncle, Samuel Powel (1738–1793).
He served as Secretary of the American Legation in London, 1807-11. During the War of 1812, he was Inspector-General of the Pennsylvania militia, and attained the rank of colonel in the U.S Army. After the war he devoted himself to agriculture, and did much to improve the breeding of cattle in the United States. He founded the Pennsylvania Agricultural Society in 1823, and published Memoirs of the Pennsylvania Agricultural Society (1824) and Hints for American Farmers (1827). He was a member of the Pennsylvania State Senate, 1827-30.
He married Julia de Veaux of South Carolina in 1817; seven of their nine children lived to adulthood. John Hare Powel, Jr. (1837–1890) served as mayor of Newport, Rhode Island. One of his daughters, Julia De Veaux Powel, married William Parker Foulke.
The Powels built a massive Greek-Revival mansion and estate in West Philadelphia, overlooking the Schuylkill River – "Powelton" (1825–32, William Strickland, architect). The mansion was demolished in 1885, and the estate developed as the neighborhood Powelton Village.