John II Orsini (Italian: Giovanni II Orsini), also John Komnenos Doukas or Comnenus Ducas (Ancient Greek: Ἰωάννης Κομνηνός Δούκας, romanized: Iōannēs Komnēnos Doukas), was a Greek-Italian noble man who rose to count palatine of Cephalonia from 1323 to 1324 and Despot of Epirus from 1323 to 1335.
His older brother Nicholas Orsini had made himself ruler of Epirus in 1318 by murdering their maternal uncle Thomas I Komnenos Doukas.
In 1331, John was attacked by Walter VI of Brienne, the titular duke of Athens, and a son-in-law of the Angevin Philip I of Taranto and Thamar Angelina Komnene.
This situation was reversed when Walter returned to the Italian Peninsula; further, in 1332, John felt strong enough to invade and annex Thessaly, which had fallen into anarchy after the death of Stephen Gabrielopoulos.
John's success provoked the immediate reaction of Emperor Andronikos III Palaiologos, who asserted his control over at least the eastern portion of the region.