Aliens are creatures indigenous to planets other than Earth. They have crash-landed or been crash-landed upon in various Muppet productions, where they have always fit, due to their naturally bizarre and unfamiliar nature.
On The Muppet Show, most of the aliens hail from the planet Koozebane, from which Kermit the Frog frequently reported. In other productions, aliens have hailed from Gorch, Mars, and other planets, both real and fictional.
Aliens have also been featured prominently in Creature Shop productions, where they have taken on more realistic forms. These aliens have been portrayed both by Creatures as well as human actors in make-up and prosthetics.