AGATHANGELUS, AGATHANGE or AKATHANKELOS, Armenian historian, lived during the 4^th century, and wrote a History of the Reign of Dertad, or Tiridates, and of the Preaching of St Gregory the Illuminator. The text of this history has been considerably altered, but it has always been in high favour with the Armenians.  It has been translated into several languages, and Greek and Latin translations are found in the Acta Sanctorum Bollandistarum, tome viii.  As known to us the history consists of three parts, a history of St Gregory and his companions, the doctrine of Gregory, and the conversion of Armenia to Christianity.