Well, that was fun
Below is a list of existing published campaign settings. To qualify to be on this list, there are three requirements: it must be by a third party publisher, it must be published and for sale (if we listed all the fan creations, the list would be impossible), and it must be for 5th Edition D&D.
- 2099 Wasteland (Legendary Games) - post-apocalyptic setting
- Adventures in Middle Earth (Cubicle 7) - Tolkien's setting of Lord of the Rings and The Hobbit.
- Aigyptos (Skirmisher Publishing) - Egyptian-themed adventures.
- Amethyst: Quintessence (Dias Ex Machina Games) - Science versus Magic, in a future Earth.
- Blood & Bone (Arcana Games) - dark, gritty setting with no gods or magic.
- Ebonclad - A Thieves' Guild Setting (Dan Coleman Productions).
- Esper Genesis (Alligator Alley Entertainment) - 5E sci-fi.
- Filbar(Adventures in Filbar) - standard fantasy setting, 5E and 1E/2E
- Godsfall Worldbook (ndependent, Aram Vartian)
- Hypercorps 2099 5E (Legendary Games) - superhero fantasy cyberpunk (also in Pathfinder)
- Land of Azurth (Hydra Cooperative) - American myth-inspired fantasy.
- The Lost Lands: Bard's Gate Player's Guide, The Lost Lands: Bard's Gate for Fifth Edition, The Lost Lands: The Blight, The Lost Lands: Borderland Provinces (Frog God Games) - high adventure in a declining empire.
- Midgard (Kobold Press) - Dark Eastern European Fantasy
- Mists of Akuma (Storm Bunny Studios) - Eastern fantasy noir steampunk.
- Neurospasta (Dias Ex Machine Games) - cyberpunk transhumanist setting.
- Parsantium: City at the Crossroads (Ondine Publishing) - Byzantium/Greco-Roman city setting.
- Ponyfinder Campaign Setting (Silver Games) - world of Everglow ruled by fey ponies.
- Primeval Thule (Sasquatch Game Studio) - dark setting inspired by Conan and Lovecraft.
- Scarred Lands (Nocturnal & Onyx Path) - Greek-inspired dark fantasy.
- Swords of Kos (Skirmisher Publishing) - Dark Ages fantasy Mediterranean.
- Tal'Dorei Campaign Setting (Green Ronin) - Matt Mercer's Critical Role setting.
- World of Farland (S. Baker) - detailed world ruled by evil.
- ZEITGEIST: The Gears of Revolution (EN Publishing) - political/urban setting with steampunk elements colliding with magic.
- Zodiac Empires (Starcalled Studios) - early industrial setting with airships.
- Lost Citadel (Green Ronin)
- Journey to Ragnarok
- Talislanta the Savage Lands
- Worlds of Empyrea (Frank Mentzer) − cancelled