Isis Unveiled by H. P. Blavatsky Isis Unveiled: A Master-Key to the Mysteries of Ancient and Modern Science and Theology, published in 1877, is a book of esoteric philosophy and Helena Petrovna Blavatsky's first major work and a key text in her Theosophical movement.

The work has often been criticized as a plagiarized occult work, with scholars noting how Blavatsky extensively copied from many sources popular among occultists at the time. Isis Unveiled is nevertheless also understood by modern scholars to be a milestone in the history of Western esotericism.

The work was originally entitled The Veil of Isis, a title which remains on the heading of each page, but had to be renamed once Blavatsky discovered that this title had already been used for an 1861 Rosicrucian work by W. W. Reade. Isis Unveiled is divided into two volumes. Volume I, The "Infallibility" of Modern Science, discusses occult science and the hidden and unknown forces of nature, exploring such subjects as forces, elementals, psychic phenomena, and the Inner and Outer Man.

Volume II, Theology, discusses the similarity of Christian scripture to Eastern religions such as Buddhism, Hinduism, the Vedas, and Zoroastrianism. It follows the Renaissance notion of prisca theologia, in that all these religions purportedly descend from a common source; the ancient "Wisdom-Religion". Blavatsky writes in the preface that Isis Unveiled is "a plea for the recognition of the Hermetic philosophy, the anciently universal Wisdom-Religion, as the only possible key to the Absolute in science and theology."