The Extremes are a group of four alien musicians who appeared in The Jim Henson Hour, Muppet Time and Muppets Tonight. The Extremes perform noises and crazy dances as they sing certain songs and scenes. These have also been in 2 Muppet Time sketches on "Alien Opera" like Ice Cream and Surprise Party. They are also featured in what Nigel refers to as the "Koozebanian dance number", indicating that they might be from Koozebane even though they have no relationship to Koozebanians.
An artwork of the extremes.
Orange Extreme
Purple Extreme
Turqouise Extreme
Yellow Extreme