Ivan Ivanovich Lappo was a Russian historian. He specialized in history of the Grand Duchy of Lithuania, especially during the late medieval and early modern period. He shared the vision prevailing in Russian historiography, namely that the union between Lithuania and Poland was enforced by the latter. However, unlike most Russian scholars of the era, he kept maintaining that the Grand Duchy retained political autonomy and remained the subject of international politics. Throughout his career, he held academic seats at the universities of Tartu, Voronezh, Prague, Kaunas and Vilnius.