Super Robot Monkey Team Hyperforce Go!/Nightmare Fuel

It's a show about robotic monkeys. It also has a Horrific Eldritch Abominations at every corner and plenty more terrors.
 * In one episode which parodied The Wicker Man, there is a secret society worshiping the bad guy who you can see the organs of, and two of its main members are a sweet couple who had been around for four seasons before this came up.
 * The episode with Wonder Fun Meat World, which featured strange meat that caused odd rashes and is addictive. And their mascot is really an Eldritch Abomination who ate humans and could stand up to the Super Robot. It vomits humans when defeated.
 * The episode with Gyrus Krinkle, an Expy of Norman Bates, in a kids show.
 * The most terrifying episode of all however, has to be I, Chiro, especially when he gets possessed.
 * The Skeleton King can be really scary sometimes, usually when he's mistreating his servants. And having Mark Hamill do the voice is part of the equation.
 * The Three-headed Monster Clown from the Circus Episode.
 * The fact that the series ends on a Cliff Hanger. Meaning ol' Skeleton King is a Karma Houdini.
 * The Episode which plays homage to HP Lovecraft with a Cthulhu Expy
 * Skeleton King