Koopas represent a consistent group of turtle-like creatures. There are many different types of Koopas, the most common being Koopa Troopas. Most Koopas seem to operate in a hierarchy-based grouping system. Bowser is the leader of the Koopa Troop, which has invaded Mushroom Kingdom many times and has control over most of the Koopas in the Mario franchise, beginning in Super Mario Bros.