"Finally, where a head can be a head." — Referring to Easter Island[source]
Old Norm Head was the original prototype for Norm's head. It makes an appearance in "Candace Disconnected"; was replaced by Norm's nowadays head, because it's always sarcastic and rude to Doofenshmirtz. In "Dance Baby", it was shown he was connected to the table. Before and after the song he was not connected. Either Doofenshmirtz installed him and then took him off, or it was just an animation goof. Then it flew to Easter Island on Doofenshmirtz's "inator".
This head has black hair like Elvis Presley, a unibrow, and a mouth which moves from side to side very often. He also has a large chin, which, if he had a body, would probably be closer to his neck than his face.
Norm v 1.0 is very sarcastic, rude, and annoying, which is the reason why Doofenshmirtz replaced him.