"Blæja" (later known as Heluna)

SOURCES

Þáttr af Ragnars Sonum (The Tale of Ragnar's Sons) says Sigurd's wife was Blaeja, daughter of Ælla.

"Sigurðr ormr í auga átti Blæju, dóttur Ellu konungs."
"Sigurd Snake-in-Eye married Blæja, the daughter of King Ella."

The Jómsvíking saga (part of Ólaf Tryggvasons' saga, which is part of Flateyjarbók) says Sigurd's wife was Heluna, daughter of Ælla.

"Sigurdr atti Helunu dottur Ella konungs."
"Sigurd married Heluna, the daughter of King Ella."

NOTE

With reference to this discussion, it seems the most accurate reconstruction of events would be that Sigurd married a woman (possibly a daughter of king Ælla of Northumbria) who's name has been lost to history. On marriage, following a Norse tradition, she gained a nickname of "Blæja" or "dark eye" (possibly in reference to her blue, black or grey eye colour) which we find preserved in Þáttr af Ragnars Sonum (The Tale of Ragnar's Sons).
Other oral traditions lost this nickname also and so by the time of the recording of the Jómsvíking saga (part of Ólaf Tryggvasons' saga, which is part of Flateyjarbók) she was assigned the name "Heluna". Ironically, Heluna is derived from the Greek Helena which we know from onomastic studies was not present in England until hundreds of years after the time frame this woman lived in.

• Reference: FamilySearch Genealogy - SmartCopy: Mar 14 2018, 15:14:41 UTC