Mykola Ivanovych Kostomarov or Nikolai Ivanovich Kostomarov was one of the most distinguished Russo–Ukrainian historians, a Professor of Russian History at the St. Vladimir University of Kiev and later at the St. Petersburg University, an Active State Councillor of Russia, an author of many books, including his famous biography of the seventeenth century Hetman of Zaporozhian Cossacks Bohdan Khmelnytsky, the research on the Ataman of Don Cossacks Stepan Razin and his fundamental 3-volume Russian History in Biographies of its main figures.