Viktor Yakovlevich Bunyakovsky (Russian: Виктор Яковлевич Буняковский; December 16 [O.S. December 4] 1804, Bar, Ukraine, Russian Empire – December 12 [O.S. November 30] 1889, St. Petersburg, Russian Empire) was a Russian mathematician, member and later vice president of the Petersburg Academy of Sciences.
He worked in theoretical mechanics and number theory (see: Bunyakovsky conjecture), and is credited with an early discovery of the Cauchy-Schwarz inequality, proving it for the infinite dimensional case in 1859, many years prior to Hermann Schwarz's works on the subject.