Mind Control (infestation) – Mind control through the use of pests, parasites, or diseases.
The Tokal is a Dungeons and Dragons parasite that can control the host (Creature Collection I).
Ceti Eel (Star Trek) burrows into ear of the victim and leaves the victim susceptible to mind control.
The parasites in The Next Generation Star Trek episode Conspiracy control their hosts and are much larger than the Ceti Eeel.
Brain Slug from Futurama