Marx

Marx (, Marx) is a character from the series, and is the primary antagonist of the  game in Kirby Super Star. He appears as a boss in Super Smash Bros. Ultimate.

Origin
Marx made his debut as a major character in the Kirby Super Star game. In the game, Marx asks Kirby to gather the power of surrounding stars to awaken the giant comet, in order to make the sun and moon stop fighting. Once Kirby finds and awakens Nova, Marx appears, knocks Kirby out of the way, and asks Nova for the ability to rule Pop Star. Nova grants Marx's wish, causing him to become larger and grow crystal wings. After Kirby defeats him, Marx is sent flying into Nova, with the impact causing them to explode.

Marx appears as the final boss of Milky Way Wishes, and, effectively, of Kirby Super Star as a whole. He also appears as the final boss of The Arena sub-game. In The True Arena sub-game from , Marx's unconscious body absorbs the remaining energy from Nova, transforming him into.

In addition to these appearances, Marx appears as the final boss in the ' sub-game, and as both a playable character and a secret boss in ', being fought during the credits sequence of the  sub-game.

In Super Smash Bros. Brawl and Super Smash Bros. 4
While Marx does not make an appearance, a remix of the theme that plays when fighting him in Kirby Super Star, Vs. Marx, appears in Brawl and Smash 4 as a music track.

In Super Smash Bros. Ultimate
Marx's boss theme from Brawl returns as a music track.

As a boss
In Ultimate, Marx appears as a boss at the end of 's, 's, and 's run,  as well as in Adventure Mode: World of Light. also faces Marx during his Classic Mode, as with other regular bosses in the game, though in the third round. Normally, plays during the battle, but  plays in Inkling's route, and  plays during the boss rush in the final stage. His voice appears similar to the one heard in Kirby Star Allies. His battle takes place in the Mysterious Dimension, which is in The Dark Realm.

Marx's boss fight starts off with him using the moves that he similarly used against Kirby in Kirby Super Star. When the fighter gets close, he will teleport some distance away from them. Marx has three moves that he didn't have in Kirby Super Star or Kirby Super Star Ultra: an attack where his eyes turn black and black balls spawn from them, an attack where he creates vein-like growths, and an attack where his eyes enlarge and fire lasers.

Upon defeat, Marx screams and starts flying around the stage sporadically. His wings break off as he reverts to his smaller form and lands face first on the ground. His body also temporarily alights in a purple flame that rises out of him just before the screen fades out.

As a costume
Marx's hat is available for the s in the shop.

Spirits
Marx also appears as two different primary spirits.

Marx can be obtained by defeating the boss in the Mysterious Dimension sub-dungeon in World of Light.

Marx (True Form) can be obtained by enhancing the Marx spirit at level 99.

Trivia

 * Marx is the only boss to be fought in Adventure Mode that does not have an area themed after his game of origin. His area appears to be a destroyed variant of various locales in the World of Light, as opposed to Planet Popstar's moon, on which he is fought in Kirby Super Star. His boss arena appears visually similar to its original appearance, however.
 * Just like in his original boss fight, players can avoid his giant laser beam by ducking under it.
 * Marx is one of three universe-representing regular bosses who had not appeared in previous Smash games; the other two are Dracula and Rathalos.
 * Marx is the only first-party boss with this distinction, as Dracula and Rathalos were made by Konami and Capcom respectively.
 * Marx is the smallest boss fought in the game, as his wings lack hurtboxes and he appears even smaller than numerous fighters.
 * Marx's arrow attack is his only attack from his original boss fight in Kirby Super Star to not appear as an attack in his Smash boss fight.
 * Marx is the only boss in the World of Light whose primary spirit is not classified as a Neutral type; instead, Marx is a Grab-type Primary spirit.
 * According to Masahiro Sakurai in "Mr. Sakurai Presents: ", Marx was initially a lot creepier and was not suitable for all audiences, so he had to be softened. It's unclear if he was referring to how Marx looked during the development of Ultimate or to his original appearance in Kirby Super Star.