Skelecogs are types of skeleton-like Cogs that lack the outer shell known as the Cog Suit. Their voices are muffled and more robotic, but they still pronounce the Cog mumbles and grumbles the same way. They behave and talk like regular Cogs, the only differences being aesthetics and vocals. Skelecogs are the only special Cog types in the Game that correspond with all known regular Cogs.
Short muscular: Specifically for Cogs with a broad chested structure, but lower ranks than top tier Cogs, like Name Droppers and Two-Faces.
Tall muscular: Majority of tier seven to eight Cogs, the highest ranking and highest-leveled ones, have this body type. Examples include Minglers, Mr. Hollywoods, and Big Wigs.
As said by Doctor Surlee, the Skelecogs invading during Doomsday were a result of the fighting Toons destroying Cogs faster than they could be produced. This was also the first time Skelecogs invaded Toontown.