Astrid Njalsdotter or Ástríðr Njálsdóttir was, according to Hervarar saga

Hervarar saga

Hervarar saga ok Heiðreks is a legendary saga from the 13th century combining matter from several older sagas. It is a valuable saga for several different reasons beside its literary qualities. It contains traditions of wars between Goths and Huns, from the 4th century, and the last part is used as...

, the Norwegian-born mother of the Swedish king Stenkil. All our knowledge about her come from this source and it reads as follows:

There was a powerful high-born man in Sweden

Sweden

Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

 called Steinkel. His mother was Astrid, the daughter of Njal Finnson the Squinter from Halogaland

Hålogaland

Hålogaland was the northernmost of the Norwegian provinces in the mediaeval Norse sagas. In the early Viking Age, before Harald Fairhair, Hålogaland was a petty kingdom extending between Namdalen in Nord-Trøndelag and Lyngen in Troms.-Etymology:...

, and his father was Rognvald the Old.

Her husband Ragnvald is usually identified with Ragnvald Ulfsson

Ragnvald Ulfsson

Ragnvald Ulfsson the Old was a jarl of Västergötland or Östergötland, and married to a sister of Olav Tryggvason.Ragnvald is mentioned in the skaldic poem Austrfaravísur, ascribed to Sigvatr Þórðarson, skald of King Olaf Haraldsson of Norway , who had been on a diplomatic mission to Sweden...

, the earl

Earl

An earl is a member of the nobility. The title is Anglo-Saxon, akin to the Scandinavian form jarl, and meant "chieftain", particularly a chieftain set to rule a territory in a king's stead. In Scandinavia, it became obsolete in the Middle Ages and was replaced with duke...

 of Staraya Ladoga

Staraya Ladoga

Staraya Ladoga , or the Aldeigjuborg of Norse sagas, is a village in the Volkhovsky District of Leningrad Oblast, Russia, located on the Volkhov River near Lake Ladoga, 8 km north of the town of Volkhov. The village used to be a prosperous trading outpost in the 8th and 9th centuries...

. This identification must however be regarded as guesswork since it is not supported by any other source. The Icelandic sagas mention a wife and two sons to Ragnvald Ulfsson but none are identical with Stenkil or his mother Astrid.