Nicolaus Cabasilas (d. 1371), Byzantine mystic and theological writer. He was on intimate terms with the emperor John VI. Cantacuzene, whom he accompanied in his retirement to a monastery. In 1355 he succeeded his uncle Nilus Cabasilas, like himself a determined opponent of the union of the Greek and Latin churches, as archbishop of Thessalonica. In the Hesychast controversy he took the side of the monks of Athos, but refused to agree to the theory of the uncreated light. His chief work is his περὶ τῆς ἐν χριστῷ ζωῆς (ed. pr. of the Greek text, with copious introduction, by W. Gass, 1849; new ed. by M. Heinze, 1899), in which he lays down the principle that union with Christ is effected by the three great mysteries of baptism, confirmation and the eucharist. He also wrote homilies on various subjects, and a speech against usurers, printed with other works in Migne, Patrologia Graeca, c. i. A large number of his works is still extant in MS.

See C. Krumbacher, Geschichte der byzantinischen Litteratur (1897), and article in Herzog-Hauck, Realencyklopädie für protestantische Theologie (1901).