Ivan Mazepa (ēvän´ məzyā´pə), c.1640–1709, Cossack hetman [leader] in the Russian Ukraine. He was made hetman (1687) on the insistence of Prince Gallitzin, adviser to the Russian regent, Sophia Alekseyevna, and he aided Gallitzin in his campaign against the Tatars (1689). Mazepa was able for some years to maintain Ukrainian autonomy while keeping good relations with Czar Peter I. Under Mazepa's direction, churches were built and libraries and educational institutions were established. He did not, however, attain his goal of uniting all Ukrainian lands (see Ukraine) with his territory, which lay on the left bank of the Dnieper River. Eventually, Peter's harsh demands on Ukraine threatened Cossack autonomy. When the Northern War between Russia and Sweden began (1700), the hetman established secret contact with pro-Swedish elements in Poland. Peter, who trusted Mazepa, refused to believe reports of his treason. In 1708, however, Mazepa openly joined Charles XII of Sweden when the latter's army advanced into Ukraine. The hetman found himself with few enthusiastic followers in this venture; most Ukrainian Cossacks remained loyal to the czar. After the Swedish defeat at Poltava (1709), Mazepa and Charles fled to Bender, where Mazepa died. According to a legend, Mazepa, in his youth, was tied to the back of a wild horse and sent into the steppes by a jealous husband. This legend was described in Lord Byron's poem, Mazeppa.

See biography by C. A. Manning (1957); studies by H. F. Babinsky (1974), O. Subtelny (1981), and T. Mackiw (1983).