Areius or Areius Didymus or Arius (Ancient Greek: Ἄρειος) was an Alexandrian philosopher of the Pythagorean or Stoic schools who lived in the 1st century BCE. He was the "personal philosopher" of the Roman emperor Augustus for a time. Areius was succeeded as "personal philosopher" of Augustus by the philosopher Theon. From Quintilian it appears that Areius also taught or wrote on rhetoric.