Boris Sidis (/ˈsaɪdɪs/; October 12, 1867 – October 24, 1923) was a Ukrainian American psychologist, physician, psychiatrist, and philosopher of education. Sidis founded the New York State Psychopathic Institute and the Journal of Abnormal Psychology. He was the father of child prodigy William James Sidis. Boris Sidis eventually opposed mainstream psychology and Sigmund Freud, and thereby died ostracized. He was married to a maternal aunt of Clifton Fadiman, the noted American intellectual.