0² (pronounced "02") is the true main antagonist and final boss of Kirby 64: The Crystal Shards, as well as the primary antagonist of the early Kirby games overall. It is the resurrected form of Zero, the creator of Dark Matter and the final boss of Kirby's Dream Land 3. It resides deep within a gargantuan sphere of amassed known as Dark Star. It continues its plans of conquest by invading the surrounding planets of Pop Star (particularly Ripple Star). Its motives for doing so are unknown, but it seems to be targeting planets possessing objects of power, such as the Crystal. In order to fight it, the player must have collected all 74 Crystal Shards, or else Miracle Matter will serve as the final boss.
Kirby 64: The Crystal Shards
Since it isn't encountered until the very end of the game, 0² stays in the background, causing disruption through its Dark Matter minions. 0² is truly the one responsible for breaking the Power Crystal on Ripple Star, and the Dark Matter infestations on several planets.
If the player neglects to collect all the Crystal Shards, then Miracle Matter will serve as a false final boss. After defeating it, the player will be treated to a cutscene of the Fairy Queen, apparently still possessed, smirking menacingly at the camera.
If all Crystal Shards are collected throughout the game, then the Crystal will fire a blast at the Fairy Queen, purging the Dark Matter from her. Our heroes then travel to the newly formed Dark Star, where Kirby and Ribbon battle Zero's revived form as the final boss. Kirby uses the Shard Gun, a weapon formed from the Crystal, during the fight, and Ribbon uses her wings to guide him around. At first, 0² is impervious to absolutely any attack. It can be stunned, however, by continuously shooting at its eye, which is seen to be bleeding when attacked. During this process, though, 0² will follow Kirby wherever he goes and constantly shoot exploding energy balls at him with decent accuracy. While it is stunned, Kirby must fly up and aim for the halo. The halo changes color each time it is hit. After enough damage is done to the halo, it disappears (and reappears after a short period of time), revealing 0²'s bandage, which only requires one hit. After shooting the bandage, 0² flips over, revealing a long green thorn-like tail on its bottom. This is its weak spot, so Kirby has to inflicting as much damage as he can before it flips back over and the whole cycle repeats; however, this is complicated by the harmful green gas clouds the weak spot generates. It is also possible to damage 0²'s wings while it is stunned, which will result in it moving much more slowly and make it lose the ability to follow Kirby. If this is done, Kirby can simply move up and attack the halo without bothering to stun 0² first.
After blasting 0²'s tail with a sufficient amount of Crystal Shards from Ribbon's Shard Gun, the entity overloads and explodes, destroying it and Dark Matter once more, ending its reign of terror on the universe for now. It should be noted however that a similar destruction happened when Kirby first beat Zero in his original form, so whether Dark Matter or Zero are truly gone remains unknown.
0² greatly resembles its previous incarnation, Zero. It has a round, white sphere as a body and a large, dark red eye (as opposed to Zero's blood red eye), with a black iris and white pupil in its center (while Zero had a black pupil lacking an iris). However, while Zero's body was completely round, the bottom of 0²'s body is slightly flat with a point at the bottom. New additions include a pair of segmented wings, a halo, a bandage at the top (only visible when Kirby flies up to attack the halo), and a tiny spike or tail on bottom. When the spike is exposed as its weak spot, it extends in length, turns bright green, and gains spines, making it look like a cactus. 0²'s wings have dark red feathers at the end, which some theorize are soaked in blood.
As Kirby enters the core of Dark Star, 0² first wears an amiable visage; two black dots resembling beady eyes above its barely open eye, which appears as a wide smile. As Kirby and Ribbon form the Shard Gun, its "mouth" opens up wide, revealing its trademark dark red eye, its false eyes disappear as the face melds together, the feathers of its wings appear, and the battle initiates.
- During the fight with 0², the "Try Again" option is replaced with "Tough It Out!". This option has the same effect as "Continue".
- The bandage on 0²'s head may be a reference to when its eye separated from the rest of its body in Kirby's Dream Land 3. This would mean that there is a gaping hole beneath the bandage left from when the eye broke away.
- 0²'s theme is an unlockable song in Super Smash Bros. Brawl by collecting at least 5,000 coins in coin matches.
- Many people have considered 0² to be one of the most disturbing bosses Nintendo has ever made (along with Giygas from EarthBound and Mad Jack from Donkey Kong 64).
- Unless all Crystal Shards are collected, Miracle Matter is the final boss. But since 0² must be defeated in order to complete the game 100%, he is the true final boss.
- Zero and 0² are the only Kirby bosses to actually hemorrhage when hit; Zero used its blood as a weapon, while 0² bleeds from its eye when attacked.