Kudeyar is a Russian legendary folk hero.

According to this legend, Kudeyar was the elder brother of Ivan the Terrible. His mother purportedly was Solomonida Saburova, whom Vasily III divorced on account of her barrenness and incarcerated in a convent. Several months after the controversial divorce she bore a son, who was smuggled to the Cossacks living along the Don River, where he became their fearless ataman and champion in the manner of Robin Hood.