Dark Matter (referred to as !? in Kirby's Dream Land 2's bad ending) is a major villain in Kirby's Dream Land 2, Kirby's Dream Land 3 and Kirby 64: The Crystal Shards. It is controlled by Zero, as well as its revived form 02. It is a shadowy sphere lined with smaller orange (originally purple) spheres, with a single eye in the middle. It usually possesses someone to help it with its goal. This is almost always King Dedede. "Dark Matter" does not necessarily refer to an individual, but rather any of a number of shadowy clouds. These clouds can amass to form a comet the size of a planet (containing Zero or Zero Two at its center) from which they can break off of to wreak havoc on Pop Star or even envelope entire planets, as shown during their attack on Ripple Star. Although Zero can be thought of as the Dark Matter clouds' collective mind, they actually appear to be a "species" capable of independent thought - Gooey is said to be "made from the same stuff as Dark Matter", suggesting he is a docile cloud who rebelled. Some generic enemies such as Nidoo and Mariel appear to be made out of Dark Matter, though not the entity's base form.
The Dark Matter race made its last major appearance in Kirby 64: The Crystal Shards, where they invaded the surrounding planets and broke the Power Crystal of Ripple Star. All of the Dark Matter clouds came together to form Dark Star, the home of Zero Two. The mass of Dark Matter was eventually destroyed once Kirby and Ribbon beat Zero Two.
Dark Matter appears in the Kirby of the Stars pilot as one of the enemies created out of the plumes of smokes when the sky went dark. It looks like the form Kirby first fights in Kirby's Dream Land 3. Kirby Freezes him with the Ice ability after he inhales the Ice Dragon. Dark Matter is drawn in Paint Panic in Kirby Canvas Curse. Dark Matter's swordsman form from Kirby's Dream Land 2 also appears in a collectible painting depicting various Kirby villains in Kirby: Squeak Squad. He is also one of the cards in Kirby Super Star Ultra's Card Swipe sub-game, again in his swordsman form.