Ælfwynn () was the ruler of Mercia as the 'Second Lady of the Mercians' for a few months in 918, following her mother's death on 12 June 918. She was the daughter of Æthelred and Æthelflæd, the rulers of Mercia. Her accession was the only example of rule passing from one woman to another in the early medieval period in the British Isles. Manuscript C of the Anglo-Saxon Chronicle (ASC C) states: "Here also the daughter of Æthelred, Lord of the Mercians, was deprived of all control in Mercia, and was led into Wessex three weeks before Christmas; she was called Ælfwynn." ASC C dates Æthelflæd's death as 12 June 918 and Ælfwynn's deposition to December 919, but most historians revise the deposition to 918. George Molyneux gives the period of Ælfwynn's power as "six or eighteen months". ASC C is the only version of the Chronicle to mention Ælfwynn. Other versions reflect a West Saxon view point and ASC A states that Edward took power in Mercia immediately after Æthelflæd's death, but ASC C includes entries from a lost version called the 'Mercian Chronicle'.