Themberchaud, the husky red dragon from Honor among thieves is well established in D&D lore. He appears in the 5e adventure Out of the Abyss. You can find a stat block for him there, but it is just a reprint of the adult red dragon stat block from the Monster Manual.
If you want something that will play a little more like the character we meet in the movie, I’ve got the stat block below for you. Themberchaud is a red dragon that has grown accustomed to a sendentary lifestyle. He has gained weight and lost the ability to fly. Although the movie depicts him with almost no ability to fly, I’ve still given him the ability to fly ten feet per turn.
The other change I’ve made is giving him the ability to create clouds of flammable gas. This ability increase the amount of damage he can deal with his breath weapon. He’ll need it to offset the fact that he can’t fly. A flightless dragon against an appropriately prepared party in D&D is a dead dragon. Themberchaud needs to pack a little more punch, or he’s a joke instead of a threat.
As usually, I’ll be deploying Themberchaud in the DungeonSports Coliseum for playtesting, and I’ll be back with updates as needed. In the meantime, you can check out the other stat blocks I’ve created.