Bobrok
Prince Dmitry Mikhailovich Bobrok Volynsky (Russian: Дмитрий Михайлович Боброк Волынский; died after 1389), also known simply as Bobrok (lit. 'little beaver'), was a Russian general, boyar, and the brother-in-law of Dmitry I of Moscow. His military prowess is glorified in the 15th-century Tale of the Rout of Mamai.