Angels, Devils, and Squid

A lot of contemporary horror fiction uses a strange blend of Christian and Lovecraftian mythology. Angels are good, but not necessarily nice. Devils are bad, but often more fun. And Lovecraftian monstrosities from Outside just want to destroy it all.

From a story perspective, it makes sense. You see it a lot in stories where God and Satan Are Both Jerks. The angels serve as foils for the hero, allowing him to show off his rule-breaking attitude. The devils prove the hero's toughness and cleverness by giving him someone to beat. And the outsiders serve as the villains of the story. Also may be a consequence of an All Myths Are True system, with angels, devils, Eldritch Abominations, The Fair Folk and the three Billy Goats Gruff all fighting with or over the protagonists.

From a theological perspective, it's a bit... muddled. Can result in The Good, the Bad, and The Evil—angels, demons, and Eldritch Abominations, respectively. If the angels are rarely seen, expect Evil Versus Oblivion (devils and squid, respectively). The Lovecraftian monstrosities may not actually be squidlike; that's just a stereotype.

Anime and Manga

 * Berserk has a lot of overlap between the three archetypes, but they do exist to some extent. The Four Elemental Kings represent the Angels, the Apostles and the Godhand that create them are the devils, and the most powerful and malevolent spiritual beings like the Sea God are the squid.

Comic Books

 * Hellboy's cosmology is rather messed up: Though devils exist (and presumably angels), most antagonists are of the tentacled variety. The biblical seven-headed dragon from the Apocalypse is made up of seven alien creatures in cocoons, while its spawn are either bugs, frogs or cephalopopds.

Literature

 * The Dresden Files actually does feature angels, devils, Eldritch Abominations, the Fair Folk, and the three Billy Goats Gruff. This means they have to take time to specify the difference between ordinary demons and Fallen Angels, and why demon-summoning is allowed under the Laws of Magic but summoning Outsiders is most certainly not.
 * Demon-summoning (as in calling up demons for information) is technically allowed, as is bargaining to get, for example, a squad of mercenary pixies for the day in exchange for a dozen pizzas. Enthralling (as in crushing free will) is one of the few laws that protects nonhuman entities, mostly because people who enslave demons do not make them volunteer at the soup kitchen. But even trying to learn about the things beyond the Outer Gates is an instant death penalty.
 * Johannes Cabal shows devils in the first book and Lovecraftian types in the third. The heavenly host have not yet been shown, but Cabal claims to know of them, and is not impressed.
 * Discworld has a pantheon that's made up of mythological expies, and in one novel shows the equivalent of Hell (although in several, Death metes out punishment to wrongdoers). On the "squid" side of things, there are the creatures from the "Dungeon Dimensions" (a reference to Dungeons & Dragons, described occasionally as resembling the offspring of a squid and a bicycle) as well as the Auditors, who due to Blue and Orange Morality are basically Omnicidal Lawful.
 * The Things crave the light and shape of "our" reality, and attempt to break through whenever some really powerful magic weakens the fabric between worlds - it's been said that if they ever succeeded, the effect would be that of an ocean trying to warm itself around a candle. They fit the "not evil so much as alien" bit mentioned above, as Rincewind realises they'd kill us without giving us "the dignity of hatred".
 * The Auditors make sure the fundamental laws of the universe continue to work, but find life-forms of any kind infuriatingly unpredictable. When they're not looking for a way to wipe out people entirely, they're trying to make us less erratic by eliminating belief.
 * J. R. R. Tolkien's 'verse has angels (the Valar) and devils (Morgoth and Sauron), the latter of whom are classic 'fallen angels' in their origins having started out as members of the angelic order. Dotted through Tolkien's creation, though, are weird primordial creatures like Ungoliant, colossal dark spider-entity of pure blight and destruction, or the unnamed beings at earth's roots. The latter are more likely to be spiders than squid, due to the author's arachnophobia, but at least one squid (the Watcher in the Water) is confirmed.
 * Middle-earth also, intriguingly, contains something of an inverse 'squid' in the shape of the being known to hobbits as Tom Bombadil: an ancient elemental force with no specific aims or objectives that simply loves existence, he seems not to be an angelic figure and takes no part in the battles between conventional good and evil, in the sure knowledge that before and after all of it he will be there still doing what he does. His only intervention is against Old Man Willow, another primordial entity that loosely fits under the 'squid' category, making Bombadil seem more akin to a 'good' counterbalance to mindless oblivion than anything.
 * A persistent fan theory is that Tom is actually an avatar of some sort for Eru Illuvatar to more freely interact with his creation.
 * The Nightside has this going on in droves, but with an emphasis on the "Squid" more than the other two. Book 2 has a blend of all three, and devils make more appearances than angels, but in a place where Eldritch Abominations walk the streets... yeah.
 * The Secret Histories books by the same author also have Angels, Devils, and Squid.
 * In Perdido Street Station by China Mieville, some of the characters try making a pact with some Legions of Hell to help them fight an escaped Abomination. It's a major Oh Crap moment when they realize not even the devil wants to go near it.
 * Kraken, by the same author, also invokes this. Albeit with a different kind of angel.
 * The Sandman Slim books by Richard Kadrey.
 * The Merkabah Rider books initially focuses on the battle between Heaven and Hell. In later stories, the Cthulhu Mythos intrudes as a third faction.

Live-Action TV

 * The mythology in Supernatural has angels from Heaven, demons from Hell, and Leviathans from Purgatory . Then there's the Fair Folk, who come from another dimension and seem to be in a different category of supernatural beings.
 * Possibly the case in Star Trek. On the side of angels, we have the Bajoran Prophets. For devils, we have the Pah-wraiths and Fek'lhr. And for squid, we have weird extradimensional beings like Species 8472, or the soul-sucking Devidians.
 * The 'verse of Buffy the Vampire Slayer and Angel is an interesting case. There are humanoid demons and angels but in the highest order, they're both squid.

Tabletop Games

 * Possibly the case in Dungeons & Dragons. Originally there was no concept of good and evil, just order and chaos. The gods were opposed by infinite demons from a place called the Abyss, which wrecked all their works. They created angels to fight the demons for them and some of those angels, while remaining loyal to the concept of order, became as destructive and cruel as the demons they faced, seeing it as necessary to do their jobs. They became the first Devils. So now there were both Lawful Evil devils, who want to take over the universe, and Chaotic Evil demons, who want to destroy it. Or so the story goes, anyway; it's just one of many versions of the creation myth...
 * There's also the bizarre creatures from the Far Realms, who have a very Lovecraftian vibe. Celestials (angels, archons, guardinals and eladrin) are pure good, fiends (devils, demons, yugoloths) are pure evil, but the creatures of the far realms are just plain alien. Expect tentacles and people going mad from encountering them.
 * Definitely the case in D&D 3.5's Spiritual Successor, Pathfinder. At least two of the base setting's gods fit the squid bill (Rovagug and Zon-Kuthon ), as well as two out of ten of The Legions of Hell (kytons and qlippoth). As well as a huge number of other critters, many of them lifed straight from the Cthulhu Mythos (including Great Old Ones and Outer Gods).
 * GURPS Dungeon Fantasy does this with the Gods from Heaven, the Demons from Hell and the Elder Things from the Outer Void.
 * It also has "nature" as a force, causing some fans to joke that the "alignments" of the game are Good, Evil, Squid and Bunny.
 * Exalted, being a Fantasy Kitchen Sink, is made of this trope. There's the gods in Yu-Shan, the Yozis and demons in Malfeas, the Neverborn and their Deathlords in The Underworld, The Fair Folk, the Alchemical Exalted and Void Lords in Autochthonia, the Mountain Folk and Darkbrood, the Dragon Kings, and pretty much anything else you can imagine, all hankering for a piece of the Creation pie for one reason or another.
 * New World of Darkness role-playing games have little in the way of angels, but some, like the Quashmallim, are present. Devils (Goetia, creatures of the Inferno) are more of a presence, but not as much as the flavors of Squid (Abyssal Intruders, elder spirits like the Idigam, Cthonians and Kerberoi in the Underworld, even The Fair Folk have strong shades of squid). The Inferno and Abyss do not get along - one wants to corrupt the material world and depends on it to survive, the other wants to destroy reality.
 * Legend of the Five Rings has the Kami on one side, the Oni on the other side, and then there is the Nothing. Which was on the receiving end of an epic butt-kicking in the previous edition.
 * Like everything else in it, this has some basis in Japanese Mythology: On one side you have the Celestial gods, on the other side you have the Terrestrial gods, and then there is the Amatsu-Mikaboshi.
 * C.J. Carella's Witchcraft RPG has this in full force, and it comes to a head with the sequel game Armageddon where the Angels and Devils have to join the Pagan Gods and other normal supernaturals to fight off a colossally powerful Eldritch Abomination and its Dark Messiah's Religion of Evil.

Video Games

 * Adventure Quest Worlds has Good, Evil, and Chaos.
 * Downplayed in Disgaea games. There are angels, devils, and aliens, but the angels might have faults, the devils might be not so evil, and the aliens aren't quite alien. All of them look very human, and the story usually revolves around a devil protagonist.
 * In Kid Icarus: Uprising, the player character, Pit, is the Angel, the Devils are, and the Squid are . Bit of a subversion, as the Angel and Devil factions team up against the squid.
 * The Command & Conquer games have GDI, Nod and the Scrin aliens who, while not really Eldritch Abominations due to having human-comprehensible motivations definitely fit the "squid" moniker.
 * Fall From Heaven mostly follows the angels and demons part of this trope, but does include the Octopus Overlords, basically directly lifted right from Lovecraft type stories.
 * Minecraft has the Nether and the End. The Nether is a Fire and Brimstone Hell, and the End is a World in the Sky where it is Always Night, the terrain is flat save for huge towers of obsidian, and the only inhabitants are Slender Man expies and a giant, nigh-unstoppable dragon.
 * It may soon be gaining an 'angels' location with a more standard-heavenly World in the Sky.
 * World of Warcraft plays with this trope. It has Angels in form of the Naaru (who look like giant glowing wind chimes, but are still the good guys), the Burning Legion for the Devils (some of whom match the classic demon descriptions along with some original designs), and the Old Gods and Faceless Ones for the Squid.

Web Original

 * The Whateley Universe has this. Phase has fought a demon and devils (in that story at least a Lovecraftian thingy), Fey led a team against Lovecraft-tainted Weres, and some of the main characters (like Carmilla) may be evolving into the squid end of the trope. Some of the secondary characters deal with the angels and devils - Seraphim is...some kind of mutant with access to possibly the Christian heaven, while Merry had to talk to and reject what may have been the actual Devil in order to become a Holy Knight.