A bogatyr or vityaz is a stock character in medieval East Slavic legends, akin to a Western European knight-errant. Bogatyrs appear mainly in Rus' epic poems—bylinas. Historically, they came into existence during the reign of Vladimir the Great as part of his elite warriors (druzhina), akin to Knights of the Round Table. Tradition describes bogatyrs as warriors of immense strength, courage and bravery, rarely using magic while fighting enemies in order to maintain the "loosely based on historical fact" aspect of bylinas. They are characterized as having resounding voices, with patriotic and religious pursuits, defending Rus' from foreign enemies and their religion. In modern Russian, the word bogatyr labels a courageous hero, an athlete or a physically strong man.

A bylina is a type of Russian oral epic poem.