My daughter’s favorite color is red. She asked me to read to her about red dragons from my monster manual. She was not pleased to hear they’re bad guys. @mikemearls can we get some nice red dragon lore? There could always be a good red dragon! An exception, but perhaps one has thrown off Tiamat's influence.
— Mike Mearls (@mikemearls) August 29, 2018
There is in the new book D&D Guildmasters’ Guide to Ravnica
Niv-Mizzet is the draconic leader and parun of the Izzet League and is at least 15,000 years old.
His intellect exceeds that of standard mortals by several echelons, and he is known for many ingenious inventions that currently serve the citizens of Ravnica, the most well known being the almost indestructible, yet easily usable and forgeable metal, mizzium.