Koopas are a race of turtle-like creatures. There are many different types of Koopas; one of the most common kinds are called Koopa Troopas.

They seem to operate in a hierarchy based grouping system. Bowser is the leader of the militaristic Koopa Troop, an organization that has attempted to conquer the peaceful Mushroom Kingdom many times. Many Koopas are soldiers in this army, and have different tasks in the organization based on the abilities of their particular class. For example, as Koopa Troopas have no special attributes, they are often assigned as the basic foot soldiers of the Koopa Troop alongside Goombas. On the other hand, Magikoopas are often given advisory roles due to their magical abilities and gift of foresight.