In Old Norse times, the people in the Nordic countries did not use surnames, only given names and primary patronyms. Some of them had a byname as well.
The primary patronyms indicated what the name of a person's father was.
To create an Old Norse primary patronym, the suffix -son (= 'son') or -dóttir (= 'daughter') is added to the genitive form of the father's name.
Name | Genitive | Son's patronym | Daughter's patronym |
---|---|---|---|
Helgi | Helga | Helgason | Helgadóttir |
Sturla | Sturlu | Sturluson | Sturludóttir |
Grímr | Gríms | Grímsson | Grímsdóttir |
Hrafnkell | Hrafnkels | Hrafnkelsson | Hrafnkelsdóttir |
The byname was a kind of a nickname used by some people in Old Norse times. You can find a long list of Viking bynames here.