Dedicated to the Transfiguration, the Pantokrator Monastery of Athos is located on the northeast coast of the peninsula, halfway between Vatopedi and Iveron. Although its foundation has traditionally been attributed to the reign of Alexios I Komnenos or to the 13th-century general Alexios Strategopoulos, the monastery is not mentioned in any sources until the second half of the 14th century. It was evidently founded in 1357 by the brothers Alexios (a megas primikerios in 1357, who became megas stratopedarches in 1358) and John (protosebastos in 1357, promoted to megas primikerios in 1358); their family name is unknown, but they were related to the Palaiologoi. The huge icon of Christ that they presented to the monastery is now in St. Petersburg. By 1394 the monastery held 15th place in the Athonite hierarchy. Sometime before Jan. 1394 Pantokrator was destroyed by fire and subsequently rebuilt with the assistance of Emperor Manuel II. In 1396 Patriarch Antony IV reconfirmed its status as a patriarchal monastery. Pantokrator had properties on Thasos, Lemnos, and Chalkidike, and a metochion near Serres. The 13 documents published by L. Petit range in date from 1357 to 1398 (plus an earlier act of 1107) and include the testament of the founder John (1384). The library of Pantokrator preserves 120 Byzantine manuscript, including the famous 9th-century marginal psalter, Pantokrator 61. From this collection, too, came the Psalter and New Testament of around 1084, now Washington, Dumbarton Oaks 3. In the katholikon are some frescoes of the 14th century, including a Deesis, the Dormition, and some figures of saints.
Oxford Dictionary of Byzantium