This paper analyzes the cases wherein a previously unknown and unique mythological character (with his/her specific behavior, “personal” traits, appearance, origin, etc.) is generated by a cultural linguistic sign or a fragment of text. This research is based on the Russian cultural and linguistic tradition, mainly in its dialectal version (the language of Russian peasants). Its sources include data published in the late 19th–early 21st century in dictionaries of Russian dialects and, primarily, the unpublished field materials of the Ural Federal University Toponymic Expedition, covering data from the Russian North, the Urals, and the Volga region. According to their nature or origin, the names of characters studied in this paper derive from two types of linguistic signs: (1) Names based on usual forms of standard vocabulary that can be both proper and common nouns; the former may refer to various categories, such as toponyms (names of geographical objects), chrononyms (names of calendar dates), hagionyms (names of saints), names of icons, etc. (2) Names originating from a text, usually folkloric; these are word combinations or phrases that only act as a single unit within their “parent” text. Sometimes, but less often, these consist of one word that is of key importance in the source text. Such a phrase or word can migrate outside the “parent” text or genre, expanding their lexical combinability and changing their syntactic regime to become a name of a mythological character. It takes two sources of motivation for a new character to emerge—a linguistic (a word that seeks a new context) and a cultural one (a semiotically intense context, such as a situation associated with danger, prohibition, omens, aggression, or magical practices). The combination of these incentives is not uncommon, so the stock of mythology used for names is being constantly renewed.