Grigory Otrepyev (born Yury Bogdanovich), according to Boris Godunov's government, was a fugitive monk who pretended to be tsarevitch Dmitry Ivanovich, the son of Ivan the Terrible and came to be known as False Dmitry  I. A son of a nobleman, Grigory was a sexton in Chudovo Monastery in the Moscow Kremlin, and once served as the secretary of patriarch Iov. Around 1582 he escaped from the monastery.

When in 1604 the impostor who passed himself for tsarevitch Dmitry crossed the Russian border and started war against Boris Godunov, the government officially announced that it was an imposter, namely the fugitive monk Grishka Otrepyev, who was anathematized. Having learned about it, the False Dmitry in some towns occupied by him demonstrated to people a person who argued that he was real Grigory Otrepyev, and Dmitry was the true tsarevitch. According to some data, Otrepyev's role was played by another monk, named Leonid. In this regard Feodor Godunov's government included in the text of the oath to the tsar the statement of refusal to support  “the one who calls himself Dmitry” in April, 1605.

After the murder of False Dmitry I the government of Vasily Shuisky IV returned to the version that the impostor was Grigory Otrepyev. The name of Grigory Otrepyev remained in the anathema list reсcited every year in the Feast of Orthodoxy Week, till the reign of Alexander II.

Lots of contemporaries doubted that the False Dmitry I and Grigory Otrepyev was the same person. Historians in general supported the official version, since there was no sufficient data able to prove or disprove it. The famous historian Nikolay Karamzin resolutely supported the Otrepyev version. On the contrary, Nikolay Kostomarov objected to identification of the impostor with Otrepyev, specifying that the False Dmitry I with his education, skills, and behavior reminded of a Polish gentleman rather than a Kostroma nobleman very well familiar with the capital monastic and court life. Moscow boyars should have known Otrepyev by sight as a secretary of patriarch Iov, and t fugitive would have hardly decided to appear before them as tsarevitch. Discussions between representatives of both the viewpoints went on even in the 20th century; newly discovered data on Otrepyev's family might explain benevolent attitude of the False Dmitry I to the Romanovs, supporters of their identity surmise. Both the opinions found reflection in the drama works about Boris Godunov written in the 19th century; Karamzin's opinion was conveyed by Alexander Pushkin in his play Boris Godunov, whereas Kostomarov's opinion was followed by Alexey K. Tolstoy in his play Tsar Boris.