A swamp dragon mentioned briefly in Men at Arms. Chubby was owned by a blacksmith in Easy Street, who was using him as a forge, to the great displeasure of Sybil Ramkin. He was brought to the Sunshine Sanctuary for Sick Dragons, but when he seemingly escaped from his pen, Lady Sybil asked Captain Vimes and the rest of the Watch to keep an eye out.
Chubby had not liked the Sanctuary - the blacksmith had not been an unkind man, and he had gotten all the coal he could eat. But in the Sanctuary, there were lots of other dragons, and people had given him unfamiliar coal. Therefore, when someone had taken him out of the Sanctuary in the middle of the night, he had assumed he was going back to the blacksmith. But d'Eath placed him in a box with a mirror right next to the Assassins' Guild's museum. The dragon, seeing an enemy in the mirror, and flamed at it until he exploded. The destruction blasted the walls of the museum apart and allowed Edward d'Eath to steal the Gonne.