Grand Prince Dmitri Ivanovich Donskoi (Дмитрий Донской, in Russian) (October 12, 1350 – 1389) was a Russian ruler (1359 – 1389).

His thirty year reign saw great changes in Russia and was the beginning of the end for Mongol domination of the nation. The Golden Horde was severely weakened by civil war and dynastic rivalries. Dmitri took advantage of this lapse in Mongol authority to advance the powers of the Princes of Moscow. He more than doubled Muscovy's territory.

While he kept the Khan's patent to collect taxes for all of Russia, Dmitri is also famous for leading the first Russian military victory over the Mongols. Mamai, a Mongol general and claimant to the throne, tried to punish Dmitri for attempting to increase his power. In 1378 Mamai sent a small Mongol army, but it was defeated by Dmitri's forces. Two years later Mamai personally lead a large force against Moscow. Dmitri met and defeated it at the Battle of Kulikovo. The next year Mamai was then defeated by a rival Mongol, Tokhtamysh. Tokhtamysh reasserted Mongol rule over Russia and pillaged Moscow for Dmitri's resistance to Mamai. Dmitri, however, pledged his loyalty to Tokhtamysh and to the Golden Horde and was returned to his position as Mongol tax collector and Prince of Vladimir. Upon his death in 1389, Dmitri was the first Grand Prince to directly bequeath his titles to his son.