548px-Bowser - Mario Party 10

Bowser, sometimes known as King Koopa (Japanese: 大魔王クッパ, Daimaō Kuppa, which can be translated into "Great Demon King Koopa" or "Great Sorcerer King Koopa", the latter meaning being used in the manual of Super Mario Bros.), is a major character and the main antagonist of Nintendo's Mario franchise. He is the leader and most powerful of the Koopas, a race of evil-driven turtles, and has been the archenemy of Mario ever since his debut in Super Mario Bros. He has repeatedly kidnapped or attempted to kidnap Princess Peach with the ultimate goal of defeating Mario and taking over the Mushroom Kingdom, though he has also attempted to conquer various other realms and even the entire universe. Despite his villainous nature, he has occasionally helped Mario and other heroes against common threats and participates with them in their numerous sporting events in spin-off games.

Since his debut, Bowser has appeared in almost every Mario franchise game. Due to his role as the primary villain in the core Super Mario series, he is mostly the final or penultimate boss in all of his appearances, if not as the main antagonist (an example being Mario & Luigi: Superstar Saga). Bowser is mostly cast as an antihero or minor villain in the franchise's role-playing games, with few exceptions.