Charr
From Multiversal Omnipedia
Charr was a burnt-out, desolate world that became the Decepticons' base of operations after they were driven from Cybertron in 2005. Apparently, there was once some sort of civilization on Charr, but a cataclysm occurred that reduced the planet to its current state.
Comments
The name is sometimes spelled "Chaar" or "Char" by fans, but the spelling "Charr" is used in the official Transformers DVD releases from Rhino.