|“||UG the Uglithug has removed the teeth from a poor little Trotterdragon in order to pretend it is the real toothless dragon from prophecy.||”|
|— How to Betray a Dragon's Hero|
The Trotterdragon is mentioned in the Prologue of How to Betray a Dragon's Hero.
The Trotterdragon is a small dragon that evidently resembles Toothless, as one was being passed off as him. More specifically, Trotterdragons must be similar to Common or Garden Dragons. The one depicted in How to Betray a Dragon's Hero appears to have a dark solid color and also have a protuberance from its forehead.
A Trotterdragon is abused and used as a fake item in the King's Things, which is necessary to pass onto the Island of Tomorrow. That particular Trotterdragon was released and went to live with the Druid Guardians on the Isle. The perpetrator - UG the Uglithug - is punished with "Death by Airy Oblivion".