Isidor Isaak Sadger (29 October 1867 - 21 December 1942), born in Neu Sandez, Galicia, was a forensic doctor and psychoanalyst in Vienna. A leader in the early development of psychoanalysis, he began his career as a neurological specialist and, in 1894, began publishing a series of articles on psychophysiology. He studied with Sigmund Freud from 1895 to 1904 with a concentration in homosexuality and fetishism and coined the term Sadomasochismus (sadomasochism) in 1913.