Abstract: The object of research is the fantasy genre, its artistic world and language. It is noteworthy that, not being satisfied with existing terms such as "occasionalisms", "proper nouns", the authors introduce new concepts. The abovementioned terms are used in the analysis and description of the linguistic features of the fantasy genre, but do not reflect the specifics of fantasy. The subject of the study is mythological sign ("mythoznak") in the fantasy genre. The material for the study is the novel "Neverwhere" by N. Gaiman, from which mythological signs were selected by continuous sampling. They are characterized by the absence of a real denotation and form the denotation space of the pseudo-world in fantasy. The theoretical significance of the work lies in deepening the understanding of the term "mythological sign" (in the context of fantasy). The practical significance of the work consists in the possibility of using the results of the research in the practice of literary translation and for educational purposes. It is revealed that a significant part of the mythological signs are author's nominations, which brings them closer to the occasionalisms. Nevertheless, they are not always created by fantasy authors: conventional language units are also used in the function of mythological signs. In this case, the author changes their structure and semantic content. On the other hand, mythological signs are not always proper names.