Bowser Koopa (Japanese 大魔王クッパ Daimaō Kuppa "Great Demon King Koopa", in English also Lord Bowser, King Koopa commonly in other media) is the supreme leader of the Koopa Troop, King of the Koopas, and the arch-nemesis of Mario. He has repeatedly, kidnapped or attempted to kidnap Princess Peach and take over the Mushroom Kingdom. He has on other occasions attempted to conquer the entire Mushroom World, as well as the entire universe.
The game Super Mario Bros. 3 introduces the first seven of Bowser's eight children, the Koopalings; who, after their first appearance in Super Mario Bros. 3, would go on to appear in several other games with their father, as well as in various other Mario-related medias, such as cartoons and publications.
Bowser's appearance is based upon a combination of the many subspecies of Koopa, including Koopa Troopas, Spinies, and Hammer Bros. Since Bowser is the King of Koopas, he possess the powers of many of the Koopa subspecies, such as Fire Bros' fire breath, Spiny's shell spikes, and Hammer Bros' hammers. Bowser's signature ability is breathing fire. He can choose to either breathe a long breath of flame or shoot many fireballs. He is often the most powerful character in sports games and can create shockwaves by doing a simple ground pound in several games. Bowser's durable nature is evident seeing that he has fallen into lava, been blown up, etc., but has managed to survive all this many times.
While Bowser has many enemies, no one has caused him more anger than Mario himself. Bowser has had a deep-rooted hatred for Mario because he has continuously disrupted his plans and won the heart of Princess Peach. Though Bowser despises Mario with a passion, he has a grudging respect for him and sees him as a worthy opponent, although he's tried to hide this reluctant respect.
Recently his latest appearance was again the final boss in New Super Mario Bros. Wii., where he appeared together with his eight children, the Koopalings and Bowser Jr.