King Koopa is the main villain of the Super Mario Bros cartoons, consisting of The Super Mario Bros. Super Show (based on the games, Super Mario Bros and Super Mario Bros 2), The Adventures of Super Mario Bros 3 (based on the game, Super Mario Bros 3) and Super Mario World (based on the game of the same name). He is modeled after the original design of Bowser in the first Super Mario Bros game. He is the arch-nemesis of the Super Mario Bros. He seeks to take over the Mushroom Kingdom and at times the real world by any means necessary. His plans are always foiled by Mario, Luigi, Princess Toadstool and Toad. He is also the father of 7 teenage Koopalings (whose names are different than they are in the games, which I honestly think their cartoon names are much better than their game names). He also often utilizes his Doom Ship (based on the Airship Fortress) and his Doom Sub (a battle sub resembling the Loch Ness Monster) for various schemes.

"I'll get those plumbers!"
-King Koopa.