B Bowser was originally envisioned as an ox based on the Ox-King from the Toei Animation film Alakazam the Great. He is a fictional character, the primary antagonist in Nintendo's Mario franchise, and the arch-nemesis of Mario.
See also: Tyus Bowser, Doug Bowser, Muriel Bowser, Mario & Luigi: Bowser's Inside Story, Bowser Jr., and Bowser's Fury.