Oleh Hornykiewicz (17 November 1926 – 26 May 2020) was a Polish-born Austrian Wolf Prize-winning biochemist. Hornykiewicz was born in Sykhiw (a district of Lviv), then in Poland (now Ukraine).
He was chairman of the Institute of Biochemical Pharmacology at the University of Vienna for twenty years. In 1967, he began a long career with the University of Toronto in Canada and, in 1992, he was named professor emeritus at that institution.
He discovered that Parkinson's disease was due to dopamine deficiency in the brain. He also played a key role in the development of L-dopa as a therapy for the disorder.
Hornykiewicz died on 26 May 2020, aged 93.