Zero (Ar tonelico II: Melody of Metafalica)

The ultimate Robot-type enemy. Although it could be said that this monster is just a reskinned Type Un-Zero, that doesn't make it any less dangerous, and in fact, due to its end-game tier stats, which include total immunity to Wind and Thunder-elemental attacks, it's far more threatening than its predecessor. It has the same skills as the Type Un-Zero, as well, so the player will have to be very careful while fighting these liquid metal horrors if they don't want to be relying on revival items during the entirety of the battle.