The true antagonist and final boss of Kirby's Dream Land 3, who turns out to be the one controlling the Dark Matter monsters which were corrupting Pop Star.
It appears as a giant white orb with a single eye and is notorious for shooting projectiles made of its own blood at Kirby and even more for ejecting its eye in the final part of the battle.
Zero also appears (presumably) in Kirby 64, as Zero Two.