Antony Antipa(983-1073) & Theodosius (1002-1074)
These two great figures were part of the Russian Orthodox Monasticism.
Antony found Russian monasteries too lax and instead lived in caves. Disciples began to gather around him and further caves had to be excavated, including larger ones for a refectory and chapel. The increase in numbers eventually led to a proper monastery being built.
Theodosius was a typical figure of Russian spirituality. He was a holy man who exercised great influence, counselling prominent people in public life and reproving them when necessary.