King Dedede

King Dedede is a large penguin-like character who is the greedy, self-proclaimed king of Dream Land. King Dedede is a recurring major antagonist in the Kirby franchise, and he has first appeared in Kirby's Dream Land. King Dedede has appeared in every Kirby game since his debut (except for Kirby & The Amazing Mirror and Kirby and the Rainbow Curse). Furthermore, since Super Smash Bros. Brawl, King Dedede has been featured as a fighter in the Super Smash Bros. series.

Mario Kirby Meisaku Video
King Dedede, alongside his rival Kirby, appeared alongside Mario in the obscure educational video Mario Kirby Meisaku Video; however, this video was merely a compilation of their non-intertwining adventures. In Kirby's Mario Kirby Meisaku Video segment, King Dedede acted as the main antagonist, where it was believed that he had kidnapped the mother of a stray puppy that Kirby befriended. In actuality, King Dedede discovered the dog to have been injured and attempted to nurse her back to health at his castle.

Super Smash Bros.
King Dedede makes a minor appearance in Super Smash Bros. as a background element who can be seen flying by on the Dream Land stage.

According to the website, King Dedede was originally planned to be a playable character, but he was cut due to time constraints.

Super Smash Bros. Melee
In Super Smash Bros. Melee, King Dedede makes an appearance as a trophy. He is also still on the Dream Land stage, which returns from the original Super Smash Bros.

Super Smash Bros. Brawl
King Dedede makes his playable debut in the Super Smash Bros. series in Super Smash Bros. Brawl. In the game, he is voiced by Masahiro Sakurai. King Dedede is one of the heaviest characters, making him slower, but similar to Kirby, he has multiple mid-air jumps, and has the fastest falling speed of any character. Dedede's hammer gives his moves range and power, but many of his attacks are slow to execute to compensate.

Dedede's standard special move is Inhale, which works similar to Kirby's move, but Dedede cannot copy opponents, and instead is only able to carry them and spit them back out as a projectile. His side special move is Waddle Dee Toss, in which he throws a Waddle Dee (occasionally a Waddle Doo or rarely a Gordo) at opponents. His up special move is Super Dedede Jump, in which Dedede leaps into the air and slams back toward the ground. His down special move is Jet Hammer, in which Dedede charges a hammer swing powered by a jet engine. Dedede's Final Smash is Waddle Dee Army, which summons Waddle Dees, Waddle Doos and Gordos to attack.

Aside from King Dedede's standard and up specials, his dash attack and forward smash originate from the Kirby games, with the former being his signature trip, while the latter is an attack he commonly uses against Kirby.

The Subspace Emissary
In the The Subspace Emissary, King Dedede learns of Tabuu's motives, and about his Off Waves, and worries that if all the fighters of the World of Trophies are all turned into trophies, then there will be no one to change them back. Therefore, he develops special brooches that are set to turn trophies back into fighters after a specific amount of time. It is also revealed through the Smash Bros. DOJO!! that King Dedede engages Meta Knight in combat as the Subspace Army takes his Halberd, though this scene was cut from the final version of Super Smash Bros. Brawl.

He is first seen attacking Luigi with his mallet and turning him into a trophy. He then hides and leaves the trophy out in the open as bait. Wario comes along with the Princess (Peach or Zelda, depending on who Kirby rescued) and Ness and sees Luigi's trophy. Wario takes it, but King Dedede's Waddle Dees come and attack Wario. Wario lets go of the Luigi trophy, which King Dedede takes. After that, he steals Wario's vehicle and drives off with the Princess trophy and Ness trophy. He later attempts to take either the Mario and Pit trophies or the Link and Yoshi trophies, until Kirby shows up and frees them. All five character chase down King Dedede. In his castle, he puts one of his brooches on all the trophies he collected, giving the one he was keeping for himself to the Princess. However, Bowser starts attacking them, turning Dedede into a trophy and after a battle, Bowser escapes with the princess trophy (who dropped the badge King Dedede put on her) and Mario, Link, Pit, Yoshi, and Kirby run away leaving the King Dedede, Luigi, and Ness trophies behind. Later, Castle Dedede is blown up by the Subspace Bomb, and the Luigi, Ness and King Dedede trophies are pulled into Subspace. Meanwhile, Kirby finds the other Dedede badge that the princess dropped and inhales it.

After Tabuu turns everyone into trophies, the brooches activate, bringing Luigi and Ness back to life, who in turn revive King Dedede as well. King Dedede then helps Ness and Luigi save everyone. When King Dedede brings Bowser back to life, Bowser attacks. However King Dedede defeats him, turning him into a trophy. Dedede then revives Bowser and before he can attack again, flicks him on the nose, then points over toward the staircase to The Great Maze.

After Kirby arrives with several more fighters, King Dedede directs them to the Great Maze. They explore the maze, defeating previously defeated bosses and battling clones of themselves. After defeating all of these, they head in to Tabuu's chamber for the final battle. Tabuu attempts to turn all the fighters back into trophies, but is ambushed by Sonic, weakening him and allowing the fighters to defeat him. Tabuu disappears and the World of Trophies is restored.

Super Smash Bros. for Nintendo 3DS / Wii U
King Dedede returns as a playable character in Super Smash Bros. for Nintendo 3DS and Super Smash Bros. for Wii U. While Masahiro Sakurai reprises King Dedede's role, he is given a more distorted voice. Several of his moves have been changed from the previous game; most of his aerial attacks are new, his side special has been changed to Gordo Throw, in which Dedede hammers a Gordo to attack opponents, and his Final Smash has been changed to Dedede Burst, which involves Dedede drawing in opponents with his suction breath before hammering them and ending with a bomb exploding on them. While most of his attributes remain relatively unchanged, he no longer has the fastest falling speed; King Dedede's air speed is slower, though other aspects of his mobility are improved. Similar to Meta Knight, King Dedede also has his overall damage output toned down.

Dedede also once again appears flying in the background of the Dream Land (64) stage that returns as downloadable content, though he does not appear if he is part of the battle.

Super Smash Bros. Ultimate
King Dedede returns as a playable character in Super Smash Bros. Ultimate where he is unlockable for the first time in the series. He has a new Final Smash, in which he traps opponents in a caged arena and fires missiles at them before finishing them off with his hammer as Masked Dedede, launching them away. This makes him one of the few fighters that have appeared since Super Smash Bros. Brawl to have a different Final Smash in each appearance (along with R.O.B., Pit, and Zero Suit Samus). King Dedede's back aerial is now a horizontal hammer swing, which has much greater range than his previous one. Aesthetically, Jet Hammer now burns with blue fire instead of orange. King Dedede's mobility is improved in all aspects, while a majority of his attacks are faster, deal more damage or knockback, or have larger hitboxes. King Dedede's down tilt is Rolling, while his dash attack is Belly Flop.

King Dedede also once again appears flying in the background of Dream Land (64), though he does not appear if he is part of the battle.

King Dedede also briefly appears in King K. Rool's debut trailer, where he pranks Donkey and Diddy Kong by wearing a King K. Rool disguise, and then proceeding to laugh hysterically at the joke he played on them before being knocked out by the actual King K. Rool.

In the Chinese version, King Dedede is the only character whose name is announced differently between the Simplified and Traditional Chinese versions: The former uses "King Dedede!" from the English version, while the latter uses "Dedede!" from the Japanese version.

Classic Mode route
King Dedede's route pits him against fighters associated with royalty.

Super Mario Maker
King Dedede also appears in Super Mario Maker as a Mystery Mushroom costume, based on his appearance in Kirby's Adventure.

amiibo

 * Every hero needs an arch frenemy, and King Dedede is Kirby’s! He calls himself the King of Dream Land, but he doesn’t have a lot of interest in ruling. His hobbies include eating, stirring up trouble, and yelling orders at his loyal Waddle Dees while bashing things with his huge hammer.

Super Smash Bros. Ultimate Super Smash Blog bio

 * He's not very fast, but he's one of few heavyweight fighters with great recovery. Apparently, a defeat by Kirby inspired him to train hard to learn a move called Hovering, which allows him to float after taking a deep breath.