|0₂ (Zero Two)|
Zero Two as seen during the final end credits of Kirby 64
|First game||Kirby 64: The Crystal Shards|
O₂ is the main villain and final boss of the Kirby game Kirby 64: The Crystal Shards. It is revealed that O₂ was the leader of the Dark Matter that attacked Ripple Star and destroyed the crystal Ribbon was holding during the opening scene of the game, before she met Kirby.
O₂'s appearance is an imperfect, white sphere, with one red eye, two wings covered in blood, a bandage on its head, a yellow halo, which changes color when hit, and has a spike at the bottom, where later a thorny vine pops out.
The requirements for battling O₂ is to collect all 100 Crystal Shards. Once the player collect the last shard, the player had to beat Miracle Matter, regardless if it was defeated before. After meeting this requirements, Dark Star is unlocked, where a small level, along with O₂ resided.
The battle takes place in the air, where Ribbon carries Kirby, who has the Crystal Ability, along with the Ribbon Ability. In order to damage O₂, the player had to fire crystals in O₂'s eye, while dodging the explosives O₂ send at Kirby. After damaging O₂'s eye enough, the player had to shoot the halo, without O₂ attacking. Once the halo was destroyed, the player had to shoot the vine coming out from below O₂, while dodging green smoke. This is the only spot where O₂'s health bar drops down. After that, the entire process start again. The player also can shoot and destroy O₂'s wings, making it slower. After the fight, O₂ gives of a bright light, and Dark Star explodes. O₂ is never seen again thereafter.
- Zero Two and Zero are known for being the only Kirby villains to ever bleed when hit.