Adelaide del Vasto, regent of Sicily, mother of Roger II of Sicily, queen of Baldwin I of Jerusalem

Adelaide del Vasto (Adelasia, Azalaïs) (c. 1075 – 16 April 1118) was countess of Sicily as the third spouse of Roger I of Sicily, and Queen consort of Jerusalem by marriage to Baldwin I of Jerusalem. She served as regent of Sicily during the minority of her son Roger II of Sicily from 1101 until 1112.