imaginary being(n = noun.person) imaginary creature - a creature of the imagination; a person that exists only in legends or myths or fiction;
is a kind of imagination, imaginativeness, vision
has particulars: hypothetical creature, mythical being, giant, hobbit, mermaid, merman, cadmus, monster, witch, character, fictional character, fictitious character, psychopomp, sylph, unicorn, death, gargantua, maxwell's demon, martian, humpty dumpty, jack frost, mammon, father christmas, kriss kringle, saint nicholas, saint nick, santa, santa claus, st. nick, tom thumb

animate being, being, come into being, extraterrestrial being, for the time being, human being, imaginary, imaginary creature, imaginary invalid, imaginary number, imaginary part, imaginary part of a complex number, imaginary place, living being, mythical being, pure imaginary number, spiritual being, supernatural being, supreme being, time being