dramatist, exponent of Expressionism, considered the most noteworthy Norwegian playwright after Ibsen.

Left alone as a child when his parents separated, he was educated at King Frederick's University, Kristiania. Heiberg's plays were always highly provocative, and their opening nights caused the greatest scandals in the history of Norwegian theatre. Paradesengen (1913) deals with the exploitation of a famous man's death by his children in such a way that it was clear to contemporary audiences that the dying hero was meant to be the beloved Norwegian writer Bjørnstjerne Bjørnson. His political plays, the ironically titled Jeg vil værge mit land (1912; “I Will Defend My Country”) and Folkerådet (1897; “The People's Council”), were violently booed. In Folkerådet some of the booing was directed against the composer Frederick Delius, who had parodied the national anthem in music written for the play.

His erotic plays mainly became known in other countries: Balkonen (1894; The Balcony, 1922) and Kjærlighetens tragedie (1904; The Tragedy of Love, 1921). In Norway, Heiberg's first play, Tante Ulrikke (1884; “Aunt Ulrikke”), has remained the most frequently performed of his works. Aunt Ulrikke is a lonely fighter for the rights of the underdog in a world ruled by an incompetent and self-serving minority.