Greek emperor of Nicaea, A. D. 1255-1259, was the son of Joannes Vatatzes and of Irene, the daughter of Theodorus I. Lascaris, from whom he derived the surname of Lascaris. His short reign presents nothing worthy of record. He died in August, 1259, in the 36th or 37th year of his age, and was succeeded by his son Joannes Lascaris. [JOANNES IV.] (Du Cange, Familiac Byzantinae, p. 223.)