The Koopa Troopas have been an ever-present staple in the Super Mario series.
The Red and Green variants first appeared in the original Super Mario Bros., and returned for The Lost Levels, as did their flying counterparts, the Koopa Paratroopas.
In Super Mario 3, both the Koopa Troopa and the flying Koopa Paratroopa return, however this time Mario has the ability to pick up and throw a Koopa shell.
Additionally, there are Giant Koopa Troopas and Giant Koopa Paratroopas, as well as an undead version called a Dry Bones.