The Fang Beasts (or, once mounted, Fang Mounts) of Horatio Cheshire were the culmination of his life's work experimenting with the humanoid races of goblins and orcs.
Once he had perfected the most lethal alterations to those creatures, he devised a new creature from scratch, using elements of many other monsters in the process. The final creation was then given over to the armies of orcs and goblins to use in the battlefield.
About
The beasts were first encountered in 825 PR on a scouting expedition funded by the Gammelgard Order of the Watchful Eye, which had been investigating the series of strange creatures emerging from the Northern Snowy Mountains.
It was later discovered that Horatio had created a secluded corral where the existing fang beasts were being bred. The original creatures were born from mutated dragon eggs. But if Horatio was to be believed, he then further mutated the existing Fang Mounts in such a way that they can now interbreed with each other. He explained that this is a unique and also disturbing accomplishment.
Notable Fang Beasts
The hero Vadath was said to have been the only non-orc to have nearly wrangled and domesticated a fang beast, riding it into many battles including The Shadow Forge Shutdown.