D&D Reskin-O-Matic! (A Knockoff of Zzarchov Kowolski's Convert-O-Tronica)

Zzarchov Kowolski wrote a super cool series of posts in 2013 he dubbed the "Convert-o-tronica" detailing a simple method of changing the flavor of a D&D adventure. I've seen other awesome ideas for "reskinning" (in video game lingo) D&D or OSR material on blogs like Rise Up Comus, Better Legends, and Dungeons & Donuts. Plus there's the excellent work of Emmy Allen. I bet that many readers can think of a multitude of other examples of reskinning projects for D&D and similar games, but these are my favorites at the moment, and Zzarchov Kowolski came up with my favorite method of doing this in a pinch.

I borrowed Mr. Kowolski's format for my own examples below. However, mine differ from (and are frankly inferior to) his examples because most of mine would probably require mechanical changes rather than just new descriptions or "fluff," and thus lack the original concept's ease of use. (That would be fine, except that I haven't provided rules or guidelines for doing so...) Still, I hope you find some enjoyable ideas here.

"Cthulhu Mythos"

Classes
Fighter = Thug or Gangster or Soldier
Magic User = Scientist or Sorcerer
Cleric = Medium or Psychic
Thief = Private Eye or Police Detective
Elf = K'nyanian
Dwarf = Deep One Hybrid
Halfling = "The Locals" (rural folk, although they need not be depicted as poorly as they tended to be in Lovecraft's writing)

Monsters
Goblin = Rat-Thing or Devolved Human
Orc = Deep One
Troll = Dark Young
Skeleton = Ghoul
Lich = The Worm That Walks
Dire Wolf = Hound of Tindalos
Dragon = Shoggoth

Pegasus = Byakhee

Dungeon Dressing
Walls = Cyclopean Basalt Blocks
Doors = Apertures opening at strange angles
"Dust" = Weird Ichor
Chests = Sarcophagi

"Krull"

Classes
Fighter = Prince or Knight
Magic User = Wizard
Cleric = Old One (wise man)
Thief = Bandit
Elf = Seer or Widow of the Web
Dwarf = Cyclops
Halfling = Apprentice

Monsters
Goblin = Evil Bandit
Orc = Slayer
Troll = Crazed Cyclops
Skeleton = Slayer without armor
Lich = Changeling
Dire Wolf = Giant Spider (possibly made of silver or crystal?)
Dragon = The Beast

Pegasus = Fire Mare

Dungeon Dressing
Walls = Either typical high fantasy pseudo-medieval architecture, or Strangely Organic Curves
Doors = Heavy Stone
"Dust" = Sand and Mud
Chests = Inexplicably safe lava

"Diablo I and II"

Classes
Fighter = Paladin
Magic User = Sorceress
Cleric = Druid
Thief = Assassin
Elf = Necromancer
Dwarf = Barbarian
Halfling = Amazon

Monsters
Goblin = Fallen One
Orc = Goatman
Troll = Overlord or Butcher
Skeleton = still a Skeleton
Lich = Succubus or Mage
Dire Wolf = Horned Demon or Hidden
Dragon = Balrog or Diablo

Dungeon Dressing
Walls = Stone and Bone
Doors = Creaky Wood
"Dust" = Bones and Brimstone
Chests = Sarcophagi, Wooden Chests, Barrels, Weapon Racks, Corpses

"Dark Souls"

Classes
Fighter = Warrior (or Bandit from Dark Souls I)
Magic User = Sorcerer or Pyromancer
Cleric = Cleric or Herald
Thief = Explorer or Thief or Mercenary
Elf = Swordsman or Wanderer or Assassin
Dwarf = Knight
Halfling = Bandit or Hunter

Start at Level 0 = Deprived

Monsters
Goblin = Hollow
Orc = Black Knight or Silver Knight
Troll = Infested Barbarian or Demon
Skeleton = Wheel Skeleton or Bloathead (or a classic Skeleton that constantly reanimates if "killed")
Lich = Pinwheel or Channeler or Gravelord Nito
Dire Wolf = Great Feline or Giant Rat
Dragon = Dragon or Drake or Hydra or Moonlight Butterfly

Dungeon Dressing
Walls = Vast and Crumbling
Doors = Metal Bars or Rotting Wood or Fog
"Dust" = Ash
Chests = Big Pots or Vases

"Bloodborne"

Classes
Fighter = Military Veteran or Violent Past
Magic User = Cruel Fate
Cleric = Noble Scion
Thief = Professional
Elf = Troubled Childhood
Dwarf = Lone Survivor
Halfling = Milquetoast

Start at Level 0 = Waste of Skin

Monsters
Goblin = Huntsman
Orc = Beast
Troll = Chapel Giant or Brick Troll
Skeleton = Mad One or Silver Lady
Lich = Celestial Emissary or Witch of Hemwick
Dire Wolf = Maneater Boar or Bloodlicker
Dragon = Amygdala or Old One

Dungeon Dressing
Walls = Brick
Doors = Stately and Solid Wood
"Dust" = Spilled Blood or Random Eyeballs Everywhere
Chests = Heavy Stone Chests

"Muddled Christian Allegory"

Classes
Fighter = Wrath
Magic User = Lust
Cleric = Pride
Thief = Greed
Elf = Sloth
Dwarf = Envy
Halfling = Gluttony

Monsters
Goblin = Heretic or Non-Believer or Satyr or Imp
Orc = Various ancient cultures painted as uniform bad guys or Whoever the crusaders are fighting this week
Troll = Nephilim or Giant
Skeleton = still a Skeleton but also a symbol of the plague or a Memento Mori figure
Lich = Angel or Demon or False Prophet
Dire Wolf = Lion or Pit Locust or Serpent
Dragon = Fiery Serpent or Demon or Archangel or Behemoth

Dungeon Dressing
Walls = Anything found in The Divine Comedy or Paradise Lost
Doors = Whatever seems symbolic of some spiritual transition at the time, I guess
"Dust" = Manna or Brimstone
Chests = Reliquary or Ark

"Philosophy"

Classes
Fighter = Logic
Magic User = Epistemology

Cleric = Ethics
Thief = Political Philosophy
Elf = Metaphysics
Dwarf = Metaphilosophy
Halfling = Aesthetics

Monsters
Goblin = The Paradox of the Heap or Moral Luck
Orc = Logical Fallacies (especially Argumentum ad baculum) or the Gettier Problem
Troll = Zeno's Paradox or the Ship of Theseus
Skeleton = P-Zombie or the Mind-Body Problem
Lich = The Problem of Evil or Solipsism
Dire Wolf = Utility Monster or the Problem of Induction
Dragon = Platonic Ideal or the Münchhausen Trilemma

Dungeon Dressing
Walls = Stereotypical Ancient Greek Architecture
Doors = Operated by Maxwell's Demon
"Dust" = Reams of paper, used coffee cups, angels on pinheads
Chests = Chinese Room, Beetle-in-a-Box