Anguirus. When Godzilla first battled another giant monster in Godzilla Raids Again, it was Anguirus that he fought. Despite being Godzilla's first ever foe, Anguirus would return in future films as an ally Godzilla, helping him against King Ghidorah, Gigan, and Mechagodzilla. It is for this reason that he makes the list. Anguirus has always been Godzilla's most loyal ally.