Athanasius III Patellarios (born Alexios Patellarios, Greek: Αλέξιος Πατελλάριος, Russian: Алексий Пателла́рий; 1597 – 5 April 1654) was the Patriarch of Constantinople in 1634, 1635 and 1652. Before his patriarchate Athanasius was metropolitan of Thessaloniki. He participated at Patriarch Nikon's book editing reforms in 1653. Athanasius was canonized as an Enlightener into the Synaxis of Athonite Venerables by the Russian Church in the 1670s. His feast date is on 2 (15) May, on the 2nd Week after Pentecost, canonized alongside Athanasius the Great.