Anthony and Theodosius
Anthony and Theodosius were sainted founders of the Russian and Ukrainian monasticism. They established the Kiev Pechersk Monastery in the 11th century. They established the Kiev Pechersk Monastery. See Saint Anthony of Kiev and Theodosius of Kiev for details.
In the Eastern Orthodox Church, their names are often listed together and they are commemorated together on September 2, while each has his own feast day as well.