Pulcheria (pəlkērˈēə) [key], 399–453, Roman empress of the East (414–53), daughter of Arcadius and Eudoxia. She became coruler with her brother, Theodosius II, and regent in 414. Theodosius remained under her influence most of his life. Pulcheria took a vow of chastity and brought an almost monastic atmosphere to the Byzantine court. At her brother's death (450) she chose Marcian as emperor and nominally married him.