Ieromonahul Matei Vlastares a fost un important canonist și imnograf din secolul al XIV-lea și autor a numeroase scrieri. He was attached to the mănăstire of the Theotokos Peribleptos in Thessalonica. His writings include theological treatises on the question of union with Rome, the isihast controversy, and translations of earlier Greek fathers.
His most famous work was the Alphabetical Collection, an encyclopedia of canon law published in 1335.
- Rev. Dr. Patrick Viscuso, "A Late Byzantine Theology of Canon Law," The Greek Orthodox Theological Review 34 (1989): 203-219.