NOVA (referred to as Galactic Nova in Kirby Super Star Ultra) is a minor character in the Kirby series, and is responsible for a few plotlines. It is a (presumed) Halcandran wish-granting comet-clock.
NOVA resembles a large yellow clock, with a catlike mouth, and large, blue, drowsy-looking eyes. It has a small hole near it's left eye, revealing circuitry and gears, that would eventually grow larger due to interior damage. It's rim is lined with seemingly random objects, such as a telescope, piano keys, a lightbulb, a pocket watch, and other tools/items.
NOVA's ability is granting any one wish anyone comes to it with. Marx abuses this power to become powerful himself.
NOVA first appears in Kirby Super Star for the NES. It is the center of the plotline for the sub-game Milky Way Wishes. A small, innocent-seeming jester named Marx appears to Kirby, asking him to end a quarrel between the sun and the moon (though it would later be revealed Marx is the cause of it). Kirby accepts the challenge, and Marx tells him that in order to stop it, Kirby must gather power from the stars around Pop Star, and use them to summon an ancient wish-granting machine known as NOVA (or, more officially, the Galactic Nova). Kirby accomplishes this, but before Kirby can make his wish, Marx immediately (and rudely) kicks the Pink Puffball out of the way, and asks for control of Pop Star. NOVA soon begins a crash course en route to Pop Star, and Marx reveals his true, bat-like form. The power from the stars that Kirby collected soon gathers around him, and provides Kirby with the almighty Starship Ability. Kirby proceeds to blast through NOVA, destroying it's "Heart", scattering it's energy everywhere. Kirby then battles and defeats Marx, who flies uncontrollably into the great machine, causing them both to explode, and neither Marx or NOVA survive. (NOVA's scattered energy and wreckage would eventually revive Marx in Kirby Super Star Ultra's True Arena mode, transforming him into the demonic Marx Soul. NOVA itself would later be restored in Meta Knightmare Ultra, found in the same game.)
In Kirby: Right Back At Ya Comic, NOVA appears as a traveling comet that holds a powerfull gauntlet. Marx manages to steal the gauntlet, but Kirby later returns it after defeating Marx. Also, Nova (YershiBear's FC) was created by this being.