Bowser aka King Koopa or King Bowser is a major character in the Mario game series and an enemy of Italian plumber Mario. Bowser is a big, turtle-like, powerful fire-breathing Koopa and a leader of Koopa Troops. Bowser was an arch-nemesis of Mario since the launch of Super Marion Bros. He is the guy who is constantly trying, and sometimes succeeding in the kidnapping of Princesse Peach. That would help Bower to defeat Mario and take over the Mushroom Kingdom. But game hero Mario will not let that happen and defeats Bowser in every Mario game. A fanart Mario progress bar for YouTube with Bowser.