King Bowser Koopa Sr., King Koopa (commonly in other media) is the main antagonist of Nintendo's Mario franchise and is the archenemy of Mario. Bowser most commonly kidnaps Princess Peach, with whom he has unrequited love for, so he can make her his queen. He is the leader of the Koopa race. Although Bowser has joined forces with Mario in a few games, he repeatedly kidnaps Peach and attempts to conquer the Mushroom Kingdom with his Koopa Troop since his first appearance in Super Mario Bros.