Cyril of Beloozero (Russian: Кирилл Бело(е)зерский, romanized: Kirill Belo(e)zersky; secular name: Kozma; 1337 – 1427) was a Russian monk. He is venerated as a saint by the Russian Orthodox Church. Cyril was a disciple of Sergius of Radonezh. In 1397, he founded the Kirillo-Belozersky Monastery in northern Russia, in present-day Vologda Oblast.