Irene Ibsen Bille (10 September 1901 – 22 February 1985) (née Irene Ibsen) was a Norwegian novelist and playwright.
She was born in Kristiania as a daughter of Prime Minister Sigurd Ibsen. She was a sister of Tancred Ibsen, paternal granddaughter of world-famous writer Henrik Ibsen and Suzannah Ibsen (née Thoresen), daughter of Bergliot Ibsen (née Bjørnson) and maternal granddaughter of Bjørnstjerne Bjørnson and Karoline Bjørnson (née Reimers).
Irene Ibsen married Danish writer Steen Andersen Josias Christopher Bille (called Josias), a member of the ancient noble Bille family, in 1930, and moved to Denmark. Her first dramatic work, Uten ansikt ('Faceless'), was published here. Kysset ('The Kiss') followed in 1965. In the same year she issued the novel Det leende vindu ('The Laughing Window'). She died in February 1985.
Irene Ibsen and Josias Bille had the following descendants, who also make up roughly a third of Henrik Ibsen's living descendants
Irene Ibsen Bille's first marriage with Mario Rocco:
http://forum.arkivverket.no/topic/137114-51681-ibsen-etterkommere-i-italia/