Abydenus (Ancient Greek: Αβυδηνός) was a Greek historian, and the author of a History of the Chaldeans and Assyrians, of which some fragments are preserved by Eusebius in his Praeparatio Evangelica, and by Cyril of Alexandria in his work against Julian. Several other fragments are preserved by Syncellus. These were particularly valuable for chronology. An important fragment, which clears up some difficulties in Assyrian history, has been discovered in the Armenian translation of the Chronicon of Eusebius.