Stephen Evodius Assemani, (1709 - ca 1782), Syrian orientalist, nephew of Joseph Simon and Joseph Aloysius, was the chief assistant of his uncle Joseph Simon in his work in the Vatican library.

He was titular archbishop of Apamea in Syria, and held several rich prebends in Italy. His literary labours were very extensive. His two most important works were a description of certain valuable manuscripts in his Bibliothecae Mediceo-Laurentianae et Palatinae codd. manuscr. Orientalium Catalogus (Flor. 1742), fol., and his Acta SS. Martyrum Orientalium.

He made several translations from the Syrian , and in conjunction with his uncle he began the Bibliothecae Apostol. Vatic. codd. manusc. Catal., in tres partes distributus. Only three volumes were published, and the fire in the Vatican library in 1768 consumed the manuscript collections which had been prepared for the continuation of the work.