The Koopa Troop (also known as the Koopa Kingdom or the Koopa Clan) is a militaristic dictatorship led by Bowser, King of the Koopas. The Koopa Troop wishes to take over the peaceful Mushroom Kingdom, and, ultimately, the entire world. In fact, the Koopa Troop has taken over the Mushroom Kingdom multiple times, and, during the events of Super Mario Bros. 3, the organization even took over most of the world.
The Koopa Troop is nearly unstoppable. Bowser has an almost unlimited supply of Goomba and Koopa soldiers at his disposable; the Koopa Troop also has an army (with tanks), a navy (with ships) and an air force (with planes). Despite having a huge military, the Koopa Troop is continuously defeated by Mario and his brother Luigi, the heroes of the Mushroom Kingdom.