Aethelgyth (852-915) was a West Saxon and Mercian noblewoman during the 9th century AD. The daughter of King Aethelwulf of Wessex and the sister of several kings, including Alfred the Great, she married Ealdorman Aethelfrith of Mercia and gave birth to Aethelstan, Eadric, Aelfstan, and Aethelwald. She died in 915.