The Zombie Horde and Frankenstein's Kingdom

There was the Zombie Horde. The Zombie Horde roamed the periphery of all all the kingdoms, perpetually attacking humans to eat their brains. The horde was ruled by non-zombie beings, a mix of humans, vampires, and others, who acted essentially as herders of the zombies. The Horde leaders would seek out humans who would willingly convert to zombie-hood because they were mortally ill and wished to continue on in some form of life. The horde leaders sold their services to various kingdoms, helping one, then helping another, in attacking populations who served as a ready source of brains for the zombies.

There was Frankenstein's Kingdom. This was a kingdom founded by one mad scientist, Victor von Frankenstein, a noble who turned his dead serfs through scientific experimentation into superhumanly powerful and intelligent beings designed to be useful to Frankenstein, with varying results. Earlier monsters were often unruly and rebelled and ran off, serving at times as powerful allies of other kingdoms or becoming powerful figures in their own right, as generals or capable lords or merchants. Later monsters were much more obedient and well-suited to their particular roles in Frankenstein’s kingdom, which, when he felt he had produced a sufficiently powerful monster army, declared himself sovereign over his land and fought off attempts by the Human Kingdom to bring him back into the fold.