Imaginary companions refer to an unseen character or object that a child names and refersto during direct play or conversations with others. Research on imaginary companions originated inthe early 20th century and has continued to the present day. A plethora of studies, primarily focusingon children, indicates that imaginary companions are not uncommon among them. However, recentforeign researchs have uncovered a certain proportion of adolescents and adults also experiencing thephenomenon of imaginary companions. This review summarizes the concept of imaginary companionsand previous research in this area. It delves into the feasibility and value of investigating imaginarycompanion phenomena in adolescents and adults. Additionally, it introduces a novel form of imaginarycompanions found in adolescents and adults known as tulpa. Lastly, it outlines the prospects for futureresearch into imaginary companions.