Zero is the secondary antagonist and final boss of Kirby's Dream Land 3. He appears as a white sphere with a single red eye. Zero makes his home in the Hyper Zone, which is a void of chaos. In the beginning of the game, he opens up a portal to the Hyper Zone and releases an army of Dark Matter into Dream Land, which spreed out and possesses multiple of Dream Land's residents. However, if Kirby collects all heart stars in the game, Kirby Will be able to enter the Hyper Zone portal and challenge a Dark Matter boss as well as Zero himself, after Zero has been defeated, his eye will detach from the body and follow Kirby around, Kirby must continue attacking the eye until it explodes and destroys Zero.
In Soul Melter EX, Void Soul slightly resembles Zero, mostly when he transforms into his Dark Matter form. He references this in his Boss splash screen.