The Most Extreme/YMMV


 * Nightmare Fuel: The episode "Horrors", epsecially the winner (parasitic worms)- some can penetrate through your skin, and then live inside you!
 * In "Odd Couples", the Greenland and Pacific sleeper sharks are sluggish in cold water, so a small bioluminescent bloodsucking copepod attaches itself to the eye and acts like a fishing lure (which also blinds the shark). Yep, having a parasite for an eye!
 * The snapper and the tongue biter louse definitely qualify.
 * "Body Snatchers":Toxoplasma, hands down. No wonder it won in this category.
 * Squick:"Gross Outs".