William de Brus, 3rd Lord of Annandale

William de Brus, 3rd Lord of Annandale (died 16 July 1212), was the second but eldest surviving son of Robert de Brus, 2nd Lord of Annandale.

His elder brother, Robert III de Brus, predeceased their father, never holding the lordship of Annandale. William de Brus thus succeeded his father when the latter died in 1194.

William de Brus possessed large estates in the north of England. He obtained from John, King of England, the grant of a weekly market at Hartlepool, and granted lands to the canons of Gisburn. Very little else is known about William's activities. He makes a few appearances in the English government records and witnessed a charter of William the Lion, King of Scotland.

He married Christina, daughter of Uhtred of Galloway, and had by her three sons:
 * Robert de Brus, Lord of Annandale (died 1226), married Isobel of Huntingdon, had issue.
 * John de Brus
 * William de Brus

William de Brus died on 16 July 1212 and was survived by his wife Christina who went on to remarry, as his second wife, Patrick I, Earl of Dunbar.