The Skellobits are enemies in Super Paper Mario.

A regular Skellobit.

They, along with Bonechill, were released from their imprisonment in the Underwhere by Count Bleck. They escaped from the dark realm and laid siege on the Overthere, in an attempt to capture the Pure Heart said to be

A Spiky Skellobit.

held by King Grambi. As Bonechill took over Grambi's abode, the Skellobits--reaching as far as the upper reaches of the Overthere Stair--attacked and imprisoned the Nimbis. Coincidentally, the invasion began shortly before Mario and Luvbi reached the Stair.