|This article contains information that does not coincide with the main series canon.|
|“||In the depths of a mysterious mirror hanging in the hall of the queen waits the dark king, Shadow Dedede! He wages battle against all comers, but Shadow Dedede's true opponent is the darkness in his own heart.”|
|— VS Shadow Dedede • Kirby: Triple Deluxe|
Shadow Dedede is the Mirror World counterpart of King Dedede and the penultimate boss of Kirby: Triple Deluxe's Extra Mode, Dededetour, where he is dueled and bested by his Dream Land counterpart at Royal Road. He later appears as one the last bosses of the game's The True Arena, where Kirby fights him. Immediately after Dedede defeats Queen Sectonia DX, the Dimension Mirror unexpectedly appears and Shadow Dedede emerges, attacking Dedede soon thereafter. The two duel until Shadow Dedede is literally shattered to pieces, allowing Dedede to enter the Dimension Mirror and confront the final boss of Dededetour, Dark Meta Knight.
Shadow Dedede strongly resembles King Dedede, with the most obvious differences being his colors (or lack thereof). Shadow Dedede's skin is pitch black, as are the edges of his robe and the ball on top of his crown. His crown and robe are a much darker shade of red, as are half of the triangles on the piece of clothing around his stomach. The other triangles are dark gray, and the edges of the piece are gray and black. The brim of his crown is dark silver, and his gloves and feet are also dark gray. Shadow Dedede's mouth is light gray, and his eyes are completely white, without any pupils, and are always angled downwards angrily. His hammer is identical in form to Masked Dedede’s, though it is also much darker than the original hammer. The base is a very dark blue-ish black, and the holes on it are silver. The edges have red and gray triangles on them and the round sides are white. The spike on top is gray and the handles is also a dark gray. Shadow Dedede's symbol is several sets of black and white circles, reminiscent of how Dedede's emblem used to look in older games.
Shadow Dedede's attacks for both phases resemble Masked Dedede's from the main mode, but tend to be stronger and come out faster; both bosses deal very heavy knockback with many of their attacks.
In this half, Shadow Dedede's most common attack is to charge his opponent and tripping, leaving one star that Kirby (in the True Arena only) can use against him; Shadow Dedede can also try to inhale Kirby/Dedede, but this attack does not differ from Dedede's usage of it in the main mode. Shadow Dedede's jump attack resembles Dedede's and leaves behind a pair of stars upon landing, but Shadow Dedede moves much faster while in the air and is more difficult to avoid. Shadow Dedede can also put down his hammer, and one side of it will open, releasing either missiles or fire. Lastly, he can approach his enemy and attempt to flatten them with his hammer, either striking twice rather than Dedede's once (creating stars on both strikes) or - if Dedede/Kirby is in the air - leaping into the air and slamming his hammer down as he lands, creating a shockwave that travels to the end of the arena in whichever direction he is facing and which disappears when it hits the edge of the arena, leaving a star in its place.
Once half of Shadow Dedede's health is gone, he will fall over and his hammer will shatter into pieces of glass, but will then be revived by a mysterious magical aura and roar. Instead of grabbing an axe from a nearby pillar (as both axe-wielding pillars having been destroyed by Masked Dedede earlier in the game), he will summon one himself. Shadow Dedede retains his tripping, jumping, and inhaling abilities from the first phase, though his jump now produces a pair of shockwaves whenever he lands. Shadow Dedede will also perform multiple combos with his axe, stepping forward which each attack. He can turn around very quickly and begin another series of even quicker attacks, and lunge forward to finish his combo, leaving three stars behind him. Shadow Dedede can briefly charge his axe before jumping into the air and slamming his axe down when he lands. He will do this several times in a row; his axe will create a substantial purple explosion around him, and five stars will appear. The Shadow king can also leap into the air and hold his axe up, releasing two waves of red electrical projectiles that proceed to fall to the arena.
What is arguably Shadow Dedede's most conspicuous attack in this phase is when he floats into the background and uses the set of triangles on his shirt as teeth in a large, Dark Matter-esque mouth. While still in the background, he will charge numerous dark spheres, and shoot them wildly across the screen before floating into the foreground and firing several larger dark spheres. Each sphere will bounce off of the top and bottom of the arena, and leave a star behind when they do so.
When Shadow Dedede is defeated, he shatters into many pieces, leaving nothing behind. He will shatter in this manner when facing both King Dedede and Kirby alike.
- The stomach mouth that appears on Shadow Dedede during one of his attacks is very similar to that of King Dedede when he was possessed by Dark Matter in Kirby's Dream Land 3 and Kirby 64: The Crystal Shards.
- As Shadow Dedede opens up the hidden mouth on his stomach, blood flies off of him, similar to the beginning of Dark Meta Knight's fight. This makes him the third boss to have bled in a Kirby game, along with 0, 02, Dark Meta Knight, and Star Dream Soul OS.
- King D-Mind, the final boss of Team Kirby Clash Deluxe, is based on Shadow Dedede.
- The music that plays during the battle against the final boss contains a remix of Shadow Dedede's theme.