Traugott Konstantin Oesterreich (15 September 1880, in Stettin (Szczecin) – 28 July 1949, in Tübingen) was a German religious psychologist and philosopher.
Oesterreich was also interested in parapsychology.
He argued against the philosophy of materialism.He was the author of Die Besessenheit (1921), a book on demonic possession.
It was translated into English in 1966.
William Peter Blatty, author of The Exorcist, was influenced by the book.