Dark Is Not Evil/Playing With

Basic Trope: Characters or creatures which could be described as "dark" are on the side of good.
 * Straight: A group that look like demons from Hell are protecting a human nursery.
 * Exaggerated: An entire planet of demons from Hell is in every other way a Sugar Bowl.
 * Justified:
 * The dark race was created by the Big Bad but rebelled.
 * They like looking intimidating and ferocious. It scares enemies off so that they don't have to fight, and it helps them frighten those who aren't as moral as themselves into behaving.
 * Inverted: Dark Is Evil/Light Is Not Good
 * Subverted:
 * A race of noble but scary looking creatures are deep-cover operatives of the Big Bad.
 * The evil looking creatures complain that everyone treats them like monsters, and when the crowd is shamed by their own prejudice the monsters take the opportunity to eat them.
 * A Stockholm Syndrome sufferer attempts to rationalize away their abusive relationship with their captor using this logic.
 * Double Subverted: A race of noble but scary looking creatures in deep cover for the Big Bad join the other side when it turns out that the Big Bad was lying.
 * Parodied: A race of demons from Hell wear "We aren't evil" t-shirts, fight crime, and have a theme song all about how they're not evil.
 * Deconstructed: Although they're not evil, everyone assumes they are, and to some extent their moral nature is influenced by their lives under such a stigma.
 * Reconstructed: Because they're not evil but everyone assumes they are, some of the most noble and good act as ambassadors to change public perception of their race.
 * Zig Zagged:
 * A fearsome-looking demon turns out to be Chaotic Stupid.
 * A pure hearted hero who looks like a demon from hell has a Super-Powered Evil Side who looks like an Eldritch Abomination. However, on closer inspection, the 'evil' side is actually a more Well-Intentioned Extremist.
 * Alice meets a character who looks like an evil monster, but turns out to be good. She then meets another character who looks like an evil monster, but despite what she learned from her past experience, the character turns out to be a Complete Monster.
 * There's a correspondence between "dark" or "light",  AND moral character.
 * Averted:
 * There is no correspondence between "dark" or "light" appearance and moral character.
 * There is no good or evil in the story.
 * Enforced: The writers want to teach the lesson "never judge a book by its cover."
 * Lampshaded: "I just assumed you were a..." "A demon? Was it the horns or the leathery wings?"
 * Invoked: A Mole who appears to be a demonic creature plays on The Messiah's good nature to convince everyone that the only evil thing about him is his appearance.
 * Defied: A race of demons from Hell strive to live up to their fiendish appearance.
 * Discussed: "What, you assume we're evil just because of the red horns, forked tail and pitchfork? What's wrong with you?"
 * Conversed: "Whoever designs all these races must have a twisted sense of humour".

Go see Dark Is Not Evil. Don't worry, he's a great trope once you get to know him.