Olcott, Henry Steel, 1832–1907, American religious leader and author, cofounder of Theosophist movement, b. Orange, N.J. After working as an agricultural scientist and a lawyer, he and Helena Blavatsky founded the Theosophical Society (1875) in New York City. In 1878, they moved the society to Adyar near Madras (now Chennai), India. Theosophy, a mixture of Eastern religion and Western occultism, has been influential in popularizing Asian philosophy in the West.
See the autobiographical Old Autumn Leaves (6 vol., 1972–75). His writings include Buddhist Catechism (1881) and Theosophy, Religion, and Occult Science (1885).