Aristides the Athenian (also Saint Aristides or Marcianus Aristides; Greek: Ἀριστείδης Μαρκιανός) was a 2nd-century Christian Greek author who is primarily known as the author of the Apology of Aristides. His feast day is August 31 in the Catholic Church and September 13 in the Eastern Orthodox Church.
General info from Wikipedia.org