Cosmas of Aetolia, sometimes Kosmas of Aetolia or Cosmas/Kosmas the Aetolian or Patrokosmas "Father Cosmas" (Greek: Κοσμάς Αιτωλός, Kosmas Etolos; born between 1700 and 1714 – died 1779), was a monk in the Greek Orthodox Church.
Saint Cosmas, the "Equal to the Apostles," was officially proclaimed a Saint by the Orthodox Church of Constantinople on 20 April 1961. His feastday is celebrated on August 24, the date of his martyrdom.
Cosmas was born in the Greek village Mega Dendron near the town of Thermo in the region of Aetolia. He studied Greek and theology before becoming a monk after a trip to Mount Athos where he also attended the local Theological Academy.
After two years Cosmas left Athos. He studied rhetoric in Constantinople for a time. In 1760 he was authorized by Patriarch Serapheim II (who had marked anti-Ottoman tendencies) to begin missionary tours in the villages of Thrace – later extended to what would form the areas of both West Greece and Northern Greece. The Patriarch had been reportedly worried at the increasing rate of Christians converting to Islam in these areas.