Oslyabya was a Russian nobleman and monk of the Trinity Lavra of Sergius who lived during the 14th century. He is primarily remembered for his participation in the Battle of Kulikovo in 1380, where he fought alongside the warrior monk Aleksandr Peresvet. According to hagiographic tradition, he accepted his monastic vows shortly before the conflict, serving as a soldier under Grand Prince Dmitry Donskoy. He is venerated as a saint within the Russian Orthodox Church and is commemorated on September 7.