Dark Bowser is Bowser's final boss in Mario & Luigi: Bowser's Inside Story. He has all the powers Bowser has, along with many dark variations as well. He seeks to cover the Mushroom Kingdom in darkness and destroy it.
Dark Bowser looks similar to Bowser, in terms of build. His skin and shell are colored dark blue. His snout, stomach, horns and spikes are noticeably paler than Bowser's. He also has Dark Star-esque red eyes. The rings around his spikes and horns are black. The most noticeable difference from Bowser and Dark Bowser is that Dark Bowser has a black mohawk.
When the Dark Star was gathering DNA from Bowser's body, Mario and Luigi tried to stop it before it succeeded. The brothers fought hard to defeat it, but apparently, it had already absorbed every piece of DNA that it needed, and it transformed into Dark Bowser, although in a ghost-like state because he was incomplete. The only parts missing were the legs, which it obtained by inhaling Dark Fawful, thus completing his form, and becoming solid in the process. He flees from Bowser, but when Bowser finds him in the secret tower of Peach's Castle, they both execute flame breath attacks that clash with each other, initiating the prologue to the final battle. Bowser overwhelms Dark Bowser, then they both curl up into a spike ball and the fight commences. Bowser again overwhelms his dark form, who gets away. Later, Dark Bowser unleashes a dark hurricane over the Mushroom Kingdom, trapping Broque Monsieur, the Blue Paratroopas and several Toads and Goombas in bubbles. Bowser is now the only one who can defeat his doppelganger.
One of Dark Bowser's attacks is throwing a boulder into the air and blasting it apart with fire, causing rocks to fall from the sky. Bowser must duck with his shell to avoid taking damage. However, he must also punch one of the rocks in front of him at Dark Bowser, who is charging a massive blast of dark fire. When the rock lands in his mouth, the attack's energy recoils and he inflicts damage on himself from the inside. If Bowser does not do this, however, he takes damage from the blast.Shell Defense to damage Dark Bowser however this method takes longer.
After taking enough damage, Dark Bowser will fall to the ground; he is then fully healed by the ingested Dark Fawful and will grow larger. He will always follow this up (assuming Bowser did not make Dark Bowser's HP fall to 0 via counter-attacking) by tossing a mixed ball of "Dark Minions" at Bowser, including dark versions of Goombas, Koopa Troopa, Thwomps, Bob-ombs, and Bullet Bills. The ball pushes Bowser back several meters, after which he must then walk back through the "Dark Minions" while dodging or countering their attacks. When returns to the field, Dark Bowser again curls up into a spike ball and tries to slam into him from above. Bowser must defend with his shell, then do it again as Dark Bowser prepares the next spike-ball slam. Bowser can avoid the second attack just by walking. When it is his turn, Bowser has to attack his stomach so that he spits up the Dark Star Core and shrinks Dark Bowser. Bowser must then inhale Dark Fawful, which Dark Bowser will try to counteract it with his own inhaling technique. Fail this part and Bowser will have to do it all over again. Successfully inhaling Dark Fawful pulls him into Bowser's belly, where the Mario Brothers must fight Dark Fawful. After several turns of fighting Dark Fawful, he will escape and return back into Dark Bowser's body, forcing the process to be repeated. Only upon Dark Fawful's defeat can Bowser give his shadowy doppelganger the final blows. Once defeated, Dark Bowser dissolves, leaving only the Dark Star, which rises into the air and explodes, restoring the Mushroom Kingdom to normal.
While Dark Bowser is incomplete, he speaks extremely slowly. However, as he becomes complete, he starts to speak fully. In the Japanese version, his speech is halted and written completely in katakana while he is incomplete. When Dark Bowser inhales Dark Fawful and is completed, he begins to speak in more natural Japanese, with kanji and no pauses.
Names in other languages