Helena Petrovna Blavatsky (Russian: Еле́на Петро́вна Блава́тская, Yelena Petrovna Blavatskaya; 12 August [O.S. 31 July] 1831 – 8 May 1891) was a Russian occultist, philosopher, and author who co-founded the Theosophical Society in 1875. She gained an international following as the leading theoretician of Theosophy, the esoteric religion that the society promoted.Born into an aristocratic Russian-German family in Yekaterinoslav, Ukraine, Blavatsky traveled widely around the Russian Empire as a child.