The Nordic alien was the disguise of Sheela O'Flaherty.
Nordic Aliens are supposed to look like humanoids, so this one resembles a blonde woman with futuristic goggles. It also wears the disguise of Space Kook that was stolen from the Crystal Cove Spook Museum.
The Nordic alien was sly, and didn't talk, nor did it try to chase or capture the gang. It ran away most of the time when the gang is around with the valuable item they intend to steal.
Scooby-Doo! Mystery Incorporated
And again with the Grey and the Reptoid stole the Blakes' Pangea car in the Blake Mansion, and drove off with it. They were chased to a highway, where they fled teh car, but eventually captured by the gang and Sheriff Bronson Stone using a net.
The Nordic Alien turned out to be Sheela O'Flaherty, who is part of a family business that involved stealing valuable things, like GPS's and cars. She steals with his father, Traveler (Grey) and her brother, Connor (Reptoid.)