Dmitri Donskoi, 1350-89, Russian hero, grand duke of Moscow (1359-89). He successfully resisted Lithuanian attempts to invade Moscow, and was the first Russian prince since the Mongol conquest who dared to wage open war on the Tatars. His great victory at Kulikovo (1380) made him a popular Russian hero, but the Tatars regained their overlordship by their successful surprise attack on Moscow in 1382.