a princely and boyar family in the Russian state in the 16th and 17th centuries.

The Mstislavskiis were descendants of Gedymin and in Lithuania bore the name Izheslavskii. Mikhail Ivanovich, who died around 1536, married the daughter of Prince Ivan Mstislavskii. During the Russian-Lithuanian wars of the early 16th century, he twice sided with Russia and twice returned to the side of Lithuania, the last time at the end of 1514. His son Fedor Mikhailovich, who died in 1540 and who was a Mstislavskii on his mother’s side, left for Russia in 1526 and received Iukhot’ as his service appanage. This remained in the possession of the Mstislavskiis until the extinction of the house. In addition, he obtained the appanages of Malyi Iaroslavets and Kremensk; he also received as kormlenie (maintenance in kind) Kashira and Myshega, but these were soon taken away. He married Anastasia, the niece of Vasilii III.

Ivan Fedorovich Mstislavskii, who died in 1586, was a prominent statesman and military figure during the time of Ivan IV and became a boyar in 1548 or 1549. He was a member of the Izbrannaia Rada (selected council) and the titular commander of the Kazan campaign of 1552 and of the campaigns in Livonia in 1559–60. With the introduction of the oprichnina in 1565, he was placed together with Prince I. D. Bel’skii at the head of the zemshchina (lands remaining under the boyar duma). After the death of Ivan IV in 1584, Ivan Fedorovich became a member of the regent’s council, but in 1585 he fell into disgrace after a struggle with Boris Godunov; he was forced to become a monk and exiled to the Kirill-Belozersk monastery, where he died.

Ivan Fedorovich had two sons: Vasilii, who become a boyar in 1577 and died in 1582; and Fedor, who was a boyar from 1576 and died Feb. 12, 1622. Fedor Ivanovich was a prominent statesman, military figure, and major landowner who possessed some 50,000 desiatiny (54,500 hectares) of land as of 1613. After the death of Tsar Fedor Ivanovich in 1598, Fedor was among the pretenders to the throne. He led the government troops during Boris Godunov’s struggle against the First False Dmitrii. He held a high post during Dmitrii’s reign but took part in the plot against him in May 1606. In 1606–07, Fedor was active in military operations against the troops of I. I. Bolotnikov. After the overthrow of Vasilii IV Shuiskii in 1610, Fedor led the semiboiarshchina (boyar government of 1610–12) and took part in the drawing up and signing of the agreement of Aug. 17, 1610, on the election of Wladyslaw, the son of Sigismund III, as the Russian tsar. He took past in the concluding session of the Zemskii sobor (Council of the Land) of 1613. Fedor remained a prominent government official during the reign of Tsar Mikhail Romanov. The Mstislavskii line became extinct with his death.