Furnace Goblins are the race of goblins that inhabit Monstru.
In one sense, they could simply be called "goblins" but since they are forced to work in furnaces so often, the name stuck. Plus, calling them "furnace goblins" further de-monsterized them... making them seem more like an engine-part than a living, breathing creature.
Are there "Factory Goblins" or "Hydraulic Goblins" or "Cleaning Goblins" other such variations?
No, not really. They're still just the Furnace Goblin variety - more or less. There used to be far more types of goblins out there, but they got bred out of the gene pool in order to have a hard-working, loyal workforce.
The only true racial variation would be "Red Goblins" which are feral, wild gobs which have never been domesticated, and they have a much lesser interest in mechanical affairs. They run the Red Goblin Circus, of course. (Which many Furnace Goblins fantasize about running off and joining.)
Read more about Furnace Goblins here!
- Daniel