Hieromonk Matthew (Blastares) (14th century) was attached to the monastery of the Theotokos Peribleptos in Thessalonica. He was a noted canonist and hymnographer and the author of numerous works. His writings include theological treatises on the question of union with Rome, the hesychast controversy, and translations of earlier Greek fathers. His most famous work was the Alphabetical Collection, an encyclopedia of canon law published in 1335.