Currently discourse of the monstrous and demonological has been intensified. These phenomena are gaining new understanding due to the processes occurring in the post-secularitanian society undergoing a succession of critical shocks. The interest in the demonic and monstrous as the manifestation of the desire tends to form a new point of view on the anthropology and man's place in the new reference frame. The judgments about the demonic and monstrous allowed creating representation of the correct, normative, standard, and normal. Hereafter the definition of the demonic and monstrous characters is presented as well as differentiation between the concepts of the demonic and monstrous is drawn through analysis of etymology of the words "demon" and "monster" and their connotations in different languages. Particular attention is drawn to the changes in the concepts of demonological and monstrous in cultural traditions and historical perspective on the basis of analysis of the ancient Greek literature, pre-Christian mythological and biblical texts, philosophical treatises and works by Plato, Thales, Socrates, Hesiod, Homer, Aristotle, Cicero, Pliny, Ctesias of Cnidus, St. Augustine, Vl. Solovyov, Av. Fr. Pott, A.F. Losev, G. Umberto Eco, Derrida, Sl. Zizek. The analysis revealed the differences in relation to the monstrous and demonic. If the idea of the demonic has evolved from the divine to the sinister, and has completely lost the binary of the semantic opposition up to now, the monstrous continues to show the duality of its nature. As a result the monstrosity is associated with limitary existence between the normal and abnormal, possible and admissible, esthetic and ugly, ethical and immoral, represented and unimaginable. If the demonic is the manifestation of the supernatural and demonstration of the Other, the monstrous as exiting outside the scope of the ordinary and habitual, represents the image of the Other. Both the supernatural of the demonic and the marginality of the monstrous ground concatenation, furnishing the images with the phantasmic. If the demonic appears as the distortion of the divine, the monstrous is the distortion of the human. The hybridous or synthetic character of the forms and qualities is the feature common to both the demoniac and monstrous images.