Parasitized undead

I got this idea while reading about chinese herbal remedies. Apparently the Chinese womens swim team some years back was accused of using performance enhancing drugs, their coach in a press conference claimed they were taking herbs including the rare and expensive cordyceps.

Cordyceps is a fungus that lives exclusively on a certain moth caterpillar, eventually killing it as it matures, feeding on the flesh of the animal.

This humanoid with some vague nematodic qualities shambles along and is driven to whatever misdeeds cross it's parasitized mind. Whether it still thinks for itself at all or is now a hapless host to a fungal entity is unknown - better to kill it first and ask questions later.