The turtle-like enemies that are in most of the Mario games. There are 2 different types of Koopa Troopas: ones with green shells and ones with red shells. Koopa Troopas that fly are called ParaTroopas. The first game you could play as a Koopa Troopa was in Super Mario Kart. When Mario jumps on a Koopa Troopa, his shells falls off, and you can jump on it, carry it, or have Yoshi eat it and spit it back. Easily one of the coolest Mario bad guys.
*MC Koopa has joined the game*
Someone:Yo wuzzup Koopa Troopa? *sings Mario theme song*