Halla is from the Old Norse hǫll (hall, stone) — feminine form of Hallr. **Halla Eyjólfsdóttir (c. 935-?)** was the medieval Icelandic woman known from the Landnámabók. Halla Tómasdóttir (born 1968) is the **current President of Iceland** (elected 2024).
Used widely in modern Iceland.
Halla reduces to nine — the number of Icelandic.