Nikolay Diletsky (Ukrainian: Микола Дилецький, Mykola Dyletsky, Russian: Николай Павлович Дилецкий, Nikolay Pavlovich Diletsky, Nikolai Diletskii, Polish: Mikołaj Dilecki, also Mikolaj Dylecki, Nikolai Dilezki, etc.; c. 1630, Kiev – after 1680, Moscow) was a music theorist and composer born in the Kiev Voivodeship of the Polish-Lithuanian Commonwealth and active in Russia. He was widely influential in late 17th-century Russia with his treatise on musical composition, A Musical Grammar, of which the earliest surviving version dates from 1677. Diletsky's followers included the Russian composer Vasily Titov.