Karion Istomin (Russian: Карион Истомин) (Late 1640s, Kursk - no earlier than 1718, Moscow) was a Russian poet, translator, and one of the first Muscovite enlighteners (student of Simeon Polotsky).
Karion Istomin was a celibate priest and then a hegumen at the Chudov Monastery. He graduated from the patriarchal school and then worked at the Print Yard in 1679-1701. Karion Istomin started as a regular scrivener, then held the post of an editor, and later became the head of the yard. He is known to have authored and translated from Latin historical, religious, and pedagogical works, including his Arithmetics (Арифметика) and the Book of Reasoning (Книга вразумления), in which Istomin admonished the 11-year-old Peter I. Also, he wrote numerous acathistuses, prayers, epitaphs, and panegyrical, congratulatory, and edifying poems. In 1690s, Istomin compiled the Small Alphabet Book (Малый букварь) and Big Alphabet Book (Большой букварь) for tsarevich Alexei Petrovich, in which the material expressed in verse was used as means for facilitating the process of learning. Karion Istomin also wrote in verse the lives of the saints, an edifying treatise for schoolchildren called Домострой (Domostroy, or Household Management), and a book named Полис (Polis), which contained characteristics of twelve different sciences and most important geographical knowledge. Being an active supporter of the Petrine reforms in Moscow, Istomin was one of the first in Russia to realize the necessity of co-education of boys and girls. He elaborated methods of school education, which would be used in Muscovite schools throughout the 18th century. Karion Istomin was buried at the cemetery of the Zaikonospassky monastery in Moscow.