Probable daughter of William d'Aubigny of Arundel and Adelisa de Louvain. Charles Cawley writes (FMG Medieval Lands database):

[AGNES ([1139/41]-). Domesday Descendants records that William Earl of Arundel donated property to Boxgrove Priory for the soul of Agnes, wife of Radulf FitzSavaric, by charter dated [1173] which does not specify the relationship between the two[14]. Considering that she gave birth to a daughter before her husband's death before 1157, Agnes was probably the first child of her parents, assuming that William 1st Earl of Arundel was her father.

m RADULF FitzSavaric, son of SAVARIC FitzCana de Beaumont & his wife Muriel de Bohun (-before 1157).]