Helena Petrovna Blavatsky, sometimes called Madame Blavatsky (1831-1891), was one of the founders of The Theosophical Society, and was one of the most leading occult teachers of the 19th century. She brought the mystical knowledge of India into the western world and wrote several important occult books, most known of which is The Secret Doctrine, published in 1884.

I’ve found a good written article about her life at: http://blavatskyarchives.com/longseal.htm for those who are interested in the biography of this extraordinary woman.