A new philosophical and anyhropological-psychological concept is needed for the alienated and radically different human being according to the nihilist Romanian-French philosopher E.M. Cioran. This concept of the not-man describes a post-anthropological subject, which is ―inhumanˮ from a psychological point of view, emphasizing estrangement and otherness in the definition of humanity. I have compared Cioran‘s provocative and unusual term with Nietzsche‘s analysis of the overman - the difference between the two concepts proceeding from two conflicting nihilist perspectives - and I also have identified the not-man in the novel of the Japanese writer Osamu Dazai, No Longer Human.