Sergei Sergeievich Korsakoff (Russian: ?????´? ?????´???? ??´??????; January 22, 1854, Gus-Khrustalny – May 1, 1900, Moscow) was a Russian neuropsychiatrist, known for his studies on alcoholic psychosis.
His name is lent to the eponymous Korsakoff's syndrome and Wernicke–Korsakoff syndrome.