|"Unnamed frog" is not an official name.|
Unnamed frog can be seen in Brain's fantasy giving him an account of some sort because of his nicknames for his friends. He gives the account to someone else after he can't make up a new name for Arthur. Although Unnamed Frog only appears in Nicked by a Name he has a few lines in it like " You've got the account" and more.
He wears a blue, green tuxedo and is a frog.