Bowser is a major antagonist (and playable character) in the game, Paper Mario: The Thousand-Year Door.
At Bowser's Castle, Bowser is seen talking with his troops until Kammy Koopa arrives with some news. She informs him that Mario is after these mystic artifacts called the Crystal Stars but Bowser doesn't seem too interested. However, Kammy Koopa says that Princess Peach was kidnapped by someone else sending the Koopa King into a rage. Bowser then hops aboard his Koopa Clown Car and makes a beeline for Rogueport with Kammy Koopa following behind.
Bowser is first fought in Glitzville at the Glitz Pit where he makes a surprising appearance after Mario has defeated the Dark Craw. In this battle, Bowser retains most of his attacks from the previous game but now has a poisonous bite attack instead of a claw attack. Bowser can still use the command removing stomp and even his fire breath. Unlike the previous game, Bowser's head is now spike forcing Mario to strictly use Hammer attacks on him and a partner that's good with dealing with spiked opponents (such as Koops). The best strategy is to use Power Smashes with Mario and a regular shell toss from Koops and Bowser will go down in no time. If Mario and company are still weakened from their battle with the Dark Craw, using Sweet Treat is recommended.
The second and final fight with Bowser serves as the penultimate fight of the game coming straight from the fight with Grodus. Bowser also fights alongside Kammy Koopa who aids him greatly in this fight. All of Bowser's attacks in this battle are the same from the previous fight except with higher attack power. Kammy Koopa can also aid Bowser in battle by powering him up or healing him and weakening Mario's party. It is highly recommended to take down Kammy Koopa first as her constant healing spells will keep Bowser longer in the battle. Vivian is a very useful partner in this fight as she can inflict constant burn damage on both Bowser and Kammy Koopa while Mario helps in racking in damage. It is also recommended to level up in this fight since this battle occurs as soon the player defeats Grodus. If not, then using Sweet Feast at the start of the battle is recommended.
- This is the first game where Bowser is fought twice in and is even a playable character. The second time will be in Super Paper Mario.