John IV Doukas Laskaris (or Ducas Lascaris) (Greek: Ἰωάννης Δούκας Λάσκαρις, Iōannēs Doukas Laskaris; December 25, 1250 – c. 1305) was the fourth emperor of the Nicaean Empire from August 16, 1258 to December 25, 1261, one of the Greek successor states formed after the Sack of Constantinople by the Roman Catholics during the Fourth Crusade.

However, this contradicts the evidence of the historians George Pachymeres and Nikephoros Gregoras, who record that John remained in Dacibyza until long after Michael's death.

In his study of Michael VIII's reign, historian Deno John Geanakoplos discusses the contradictory evidence and comes to the conclusion that the documents of Charles of Anjou were intended to serve as propaganda, "to attract the support of the legitimist, pro-Lascarid Greeks of the Byzantine Empire, as well as to sway the anti-Angevin sentiment of the still surviving Greek population of Charles' own territories of southern Italy and Sicily.

"[3] In 1290 John was visited by Michael VIII's son and successor Andronikos II Palaiologos, who sought forgiveness for his father's blinding three decades earlier.

As Donald Nicol notes, "The occasion must have been embarrassing for both parties, but especially for Andronikos who, after all, was the beneficiary of his father's crimes against John Laskaris.