I'm not sure of the origins of the Helle name other than the fact that my grandmother's maiden name was Helle. She was from the coast of Norway orginally and kept her surname from Norway (meaning, they did not change her surname when she came through Ellis Island). I have a second cousin by the name of Trygve Helle. He lives in Washington State. I believe he has some information on the orgins of the name Helle and whether the surname is unusual or if it's like Smith or Jones (that'd be my luck). Hopefully this may be of some help.