Ambrose of Optina was a 19th-century Russian Orthodox monk and hieroschemamonk who served as a prominent spiritual elder. Born Aleksandr Grenkov in 1812, he entered the Optina Monastery in 1839 following the advice of an elder named Hilarion. Despite facing chronic health challenges throughout his life, he became a central figure at the monastery, serving as its principal elder for three decades after 1860. He is recognized as a saint and a wonderworker within the Eastern Orthodox tradition.