Little is known about her except her marriage to Ethelred. Among their children was the future Edmund II Ironside. She died in 1002, and Ethelred then married Emma of Normandy.
Canute the Great, who married Emma when Ethelred was deposed, had a mistress who was also named Elgifu, although she was not the same Elgifu that had been married to Ethelred. With this Elgifu, Canute had a son, Harold, who later became Harold I of England.
Elgifu, a popular female name among the Anglo-Saxons, was also the name of the wife of King Edgar the Peaceable.
Eadwig, the elder son of Eadmund, who then came to the throne, was a dissolute and headstrong youth, wholly devoted to the reactionary party and entirely under the influence of two unprincipled women.
These were Aethelgifu, a lady of high rank, who was perhaps the king's foster-mother, and her daughter Aelfgifu, whom she desired to marry to Eadwig.
On the day of his coronation, in 956, the king abruptly quit the royal feast, in order to enjoy the company of these two women.
Two years later, Canute started to lay claim to Norway, eventually capturing it and putting his son Svein and his mistress Aelfgifu to govern it.
Scotland also submitted to Canute and, by the late 1020s, Canute was able to claim to be 'king of all England, and of Denmark, of the Norwegians, and part of the Swedes'.
Aelfgifu's son, Harald, became king of England but died in 1040.