Venerable Saint Joannicius the Great, in original Greek Ioannikios the Great (Greek: Όσιος Ιωαννίκιος ο Μέγας 752, village Marikat, Bithynia - † November 4, 846 in Antidium) - respected Byzantine Christian saint, sage, theologian, prophet and wonderworker, the hermit of Mount Olympus (today known as Uludağ, near ancient Prussa, modern Bursa, Turkey), monk and abbot. One of the greatest monks of Christian East.
His feast day is November 4 (in Catholic Church, new Gregorian calendar) / November 17 (in Orthodox Church, old Julian calendar)