MULLER, or REGIOMONTANUS, JOHN, a celebrated astronomer of the fifteenth century, was born at Koningshoven, in Franconia, in 1436, and acquired great reputation by publishing an abridgment of Ptolemy's Almagest, which had been commenced by Purbach. He went to Rome to perfect himself in the Greek tongue, and to visit Cardinal Bessarion; but finding some faults in the Latin translation of George de Trebizond, the translator's son assassinated him in a second journey which he made to Rome in 1476, where Pope Sixtus IV. had provided for him the archbishopric of Ratisbon, and had sent for him to reform the calendar. But others state that he died of the plague.