Nikolai Ustryalov

Nikolay Gerasimovich Ustryalov (; 4 May (N.S. 16 May) 1805 in Bogorodickoye, Oryol Governorate, Russian Empire – 8 June (N.S. 20 June) 1870 in Tsarskoye Selo, Russian Empire) was a Russian Imperial historian who elaborated the Official Nationality Theory. His outline of Russia's history was awarded the Demidov Prize for the best Russian history textbook and was highly regarded by Nicholas I himself.

Ustryalov's father was a peasant, and his grand nephew Nikolay Vasilyevich Ustryalov was a notable politician. His major contributions to Russian historiography include the publication of several key sources on the Russian Tsardom such as Jacques Margeret's memoir (1830), the collection of reminiscences about False Demetrius I (1831), and Andrey Kurbsky's complete writings (1833).

Ustryalov's lectures in the University of St. Petersburg grew increasingly unpopular with students during Alexander II's liberal reign. He spent the latter part of his life working on the ten volumes of The History of Peter the Great's Reign, of which however only volumes 1-4 and 6 were completed. This work was highly regarded by his contemporaries.