The theme of bizarreness was not only of interest for the alienist psychiatrists of the 19th century but also for Freud in The Interpretation of Dreams. But the concept of bizarre object arising from profound hatred for reality, was described by Bion. At the same period, Winnicott also dwelt on this hatred and elaborated the notion of ego-alien or ego-other associated with the sudden emergence of an unconscious element destroying the ego. At their origin there is a drive to dominate a terrifying Other in the unconscious. The contributions of Guy Rosolato on demarcation signifiers coincide with Bion and Winnicott’s investigations.