Lascaris (lăsˈkərĭs) [key], family name of the Greek emperors of Nicaea (see Nicaea, empire of). The empire was founded in 1204 by Theodore I, a son-in-law of Alexius III (Alexius Angelus). Theodore I was succeeded (1222) by his son-in-law, John III (John Ducas Vatatzes). John's son Theodore II (1254–58) assumed the family name Lascaris. He was succeeded by his son John IV, who was forced (1259) to share his throne with Michael VIII, founder of the Palaeologus dynasty. John was deposed in 1261.