Lady Vataça Lascaris (Ventimiglia, 1268 – Coimbra, 1336), also referred as Vatatsa Lascaris, Vataça of Ventimiglia, Dona Betaça, Betaça de Grécia, Vatatsa or Vetacia was an Italian princess of Byzantine Greek origin.
Lady Vataça was the daughter of Princess Eudoxia Laskarina (1254–1311) of the Empire of Nicaea and Guillermo Pietro I, Count of Ventimiglia and Lord of Tende (~1230-1278). Eudoxia was the fourth daughter of Theodore II Laskaris and sister of young emperor John IV Laskaris, who was withdrawn from the throne by co-regent Michael VIII Palaiologos in 1261. After the conquest of Constantinople, Michael proclaimed himself sole ruler, blinding and displacing the young emperor and marrying the remaining princesses to foreigners. Eudoxia, still a child, married in 1261 in Constantinople with Count Pedro of the House of Ventimiglia and Tende (a region that retains the Byzantine double-headed eagle as a symbol), traveling then to Liguria.
At the same time must have fled from the Byzantine court Constance II of Hohenstaufen (Ann of Sicily) (1230–1307), widow empress of John III Doukas Vatatzes (c. 1193-1254) Eudoxia's grandfather, returning to her native Sicily were her brother Manfred of Sicily ruled. In 1266, after the death of Manfred and conquest of Sicily by Charles of Anjou, Constance fled to Arangon where her niece Constance of Sicily (1249–1302) was consort of Peter III of Aragon and mother of Elisabeth of Aragon. Eudoxia also sought Aragon to escape Angevin dominance of Genoa or/and by the time her husband died. Both Byzantine noble ladies where protected and respected at the court, probably given their importance in the medieval fights and diplomacy between Aragon, Sicily and Byzantine Empire, thus explaining Vataça and Queen Elisabeth proximity, friendship and interests.
Lady Vataça came to Portugal with Elizabeth of Aragon, for the wedding with King Denis of Portugal in 1288. Court lady and friend of the future Saint Elizabeth of Portugal, to whom she was related as a descendant of Andrew II of Hungary father of Saint Elisabeth of Hungary, she was charged with the education of her children. In 1302 she followed the first born Constance of Portugal to Castille, for her wedding with Ferdinand IV of Castile, to seal the peace between the two kingdoms. There she stood until Constance’s death, who had left her infant Alfonso XI of Castile on her guard while traveling to Avila, where the court was to decide about the tutorship of the infant king. Constance died in this travel and Vataça returned to Portugal.
In 1317, Lady Vataça established a small court in Santiago do Cacém castle, given to her by King Denis in 1310/15, were she dedicated herself to the administration of her large possessions until 1325 or 1332, when she followed Queen Elisabeth to Coimbra. She died there in 1336 and her impressive tomb in the Old Cathedral of Coimbra, attributed to Mestre Pero sculptor, is surrounded by double-headed eagles, symbol of the Laskaris dynasty and the Byzantine Empire.