Character: dry bowser
Dry Bowser is the undead and skeletal version of Bowser, with his name playing off of Dry Bones. Despite not technically being one himself, he is closely associated with them and shares several traits with the species, like an immunity to fireballs. He made his debut in New Super Mario Bros., where he ascended as the result of Mario defeating Bowser by dropping him into lava at the end of New Super Mario Bros.'s first castle. Dry Bowser is then fought in the first castle in World 8.
Since his debut, Dry Bowser has made subsequent appearances, usually as a separate character from normal Bowser, the first of which was as an unlockable driver in Mario Kart Wii. Notably, he has appeared as an antagonist in the Mario & Sonic series. His appearance in both New Super Mario Bros. 2 and Super Mario 3D Land is not due to Bowser falling in the lava, as in both cases he is not turned into a skeleton after falling in the lava after the final boss battles.
The above text is from the Super Mario Wiki and is available under a Creative Commons license. Attribution must be provided through a list of authors or a link back to the original article. Source: https://www.mariowiki.com/Dry_Bowser