John IV - Basileus of the Empire of Nicea from 1258 to 1261
John IV was emperor of Nicaea from August 18, 1258, to December 25, 1261. This empire was one of the Greek states formed from the remaining fragments of the Byzantine Empire, after the capture of Constantinople by Roman Catholics during the Fourth Crusade in 1204.

John IV was only seven years old when he inherited the throne on the death of his father. The young monarch was the last member of the Laskarid dynasty, which had done much to restore the Byzantine Empire. His regent was originally the bureaucrat George Mouzalon, but Mouzalon was murdered by the nobility, and the nobles' leader Michael Palaiologos usurped the post. Soon, on January 1, 1259, Palaiologos made himself co-emperor as Michael VIII.

After Michael's conquest of Constantinople from the Latin Empire on July 25, 1261, John IV was left behind at Nicaea, and was later blinded on Michael's orders on his eleventh birthday, December 25, 1261. This made him ineligible for the throne, and he was exiled and imprisoned in a fortress in Bithynia.
John IV
Emperor John IV of the Empire of Nicea