Enslaved: Besides those already present from the parent show, the author expands and alters some of the cultural parallels. Most visibly, the Water Tribe is based on the Inuit in the show, but in the service of actually being able to have lots of outside scenes and a slightly less subsistence-level culture, the fics version is much more heavily based on Pacific Northwest native cultures, something especially visible during the salmon run arc.
Maria Campbell of the Astral Clocktower: As in canon, Sorcier is the equivalent of some European country, and while it's probably England there's not enough detail to be absolutely sure. Ashina is definitely the equivalent of Japan, which is why Katarina (a reincarnate from Japan) can speak Ashinago perfectly, to everyone's shock. While we don't see it directly, it's implied that it's specifically the setting of Sekiro: Shadows Die Twice, and that the game is happening at approximately the same time as the fic even if it's too distant to have a direct effect. Of course, this is all further confused by the fact that the fic is a distant future of the Dark Souls universe, changing the political and religious landscape significantly.
The Discworld fics of A.A. Pessimal take Terry Pratchett's Fantasy Counterpart Cultures up to eleven. Pratchett's structure (Quirm = France, Überwald = Switzerland/Bavaria/Germany, Llamedos = Wales, et c) is expanded on with additions such as Rimwards Howondaland = South Africa, the Sto States = Benelux note Sto Helit, a Grand Duchy, = Luxembourg, Sto Lat = Belgium, Sto Kerrig = Holland , Far Überwald/Zlobenia = Russia, "Aceria" = Canada, Eh? mixed with Eagleland, Hergen = Ireland, et c. As can be expected, National Stereotypes abound: Sto Kerrig is renowned for windmills, clogs, tulips, strange smoking tobaccos, and a language shading from "Kerrigian" into "Phlegmish" that sparked off a daughter dialect spoken in "Hovondalaand".
The Skagosi are a counterpart of the Alaskan and British Columbian tribes such as the Tlingit and Haida. Skagosi characters wear cedar hats and button blankets, both items of clothing iconic the aforementioned tribes.
The Crannogmen have Cajun elements, especially in regards to their food.
The Manderlys are given a very Greek aesthetic, which works given their sigil is Poseidon in all but name.
Before and Beyond the Beginning does a Perspective Flip. One of the issues between Lions and Hyenas is their Culture Clash, between the passive Circle of Life and the brutal Food Chain, which is about survival of the fittest. It is not entirely heartless either, with Shenzi pointing out that being higher on the Food Chain doesn't make you better than other people, it just means you get to eat them, and encourages gratitude for both what you have and what you get.
My Little Pony: Friendship Is Magic fanfiction features these often, due to both their presence in the show itself, the relative ease of creating them by making an animal pun on a preexisting nation's name, and the established associations various animals and mythical creatures have with specific behaviors and real-life cultures.
The Bridge: Ki Seong is a Kirin from Carrea, Equestria's version of Korea. There is also an island nation called Neighpon which resembles Japan.
Under the Northern Lights: Tarandroland is a mix of modern and medieval Scandinavia. The nomadic "Grazer" reindeer are obviously a counterpart to the Sami people, though with much more power and influence. Unlike modern Scandinavia, Tarandroland is pretty much a third world country, however. There are other examples: "camel sultanates" and ki-rin ruled by a "Mikado" are mentioned, and Equestria is treated as similar to USA.
The Palaververse: Besides those already present in the My Little Pony: Friendship Is Magic canon, Asinia is Spain at the height of the colonial age, Capra shares quite a bit with the various Persian empires, Ovarn is a more united version of the Greek city-states, Bovaland is feudal Europe, the Corvids are the Scottish highland clans, Zebrica is Pharaonic Egypt, the continent of Dactylia in general stands in for Africa, the mammoth clans of the southern Dactylian steppes have a distinctly Mongolian flavor, and Ceratos has elements of imperial China and Japan, with the nation's tapir minority taking the role of the Ainu people.
Norkia for, well, North Korea. Also a pun, as the Norkians are functionally "orcs" in this tale even though they are actually ponies.
A Long Night at the Hippodrome: Numerous. The main setting, Baltimare, is a parallel to Baltimore. The titular Hippodrome exists in the real city, and it was built by two impresarios, Pierce and Scheck, corresponding to the in-story characters Piercing Gaze and Russe Tinter in-story. Besides that, the Yehvist Onagers stand in for the Jews, the Onagers for Semites in general, Germaney for Germany and Lippans for Austria.
The Lunar Rebellion: Pegasopolis is mostly based on ancient Sparta (the Ephorate, the Gerousia, a legendary lawgiver named Lyequinegus, a disdain for money, etc.) and ancient Rome (clans led by a paterfamilias, adoption, damnatio memoriae, etc.), although the hetairoi were an ancient Macedonian unit.
Maternal Instinct (MLP): The changeling society is heavily based on early twentieth-century Imperial Japan. The griffon kingdom is apparently Germany, going by their language and love of Zombie Apocalypse movies. Their leader's title is also "Kaiser".
The Old Kingdoms are largely expies of European nations. Prance is France, Hackney is the UK, Germaneigh is Germany, Trotugal is Portugal and Espanya is Spain.
The Marelantian Isles are the Caribbean Isles.
The Halla deer-folk are a merging of the Vikings and Native Americans.
Zebrica is Africa.
The griffin aeries are Byzantium, with a bit of the Italian city-states. The old griffin empires before the fracture are based on Rome.
Starlight Over Detrot: The Arroyo Cyclones are Haitian diaspora, what with their Caribbean accents and adherence to Vodou. Griffins are Scotirish, as they're organized into clans, wear kilts, and speak an Oirish brogue.
RWBY: Scars: The different kingdoms take a bit more inspiration from real world countries than in canon. For example, though most people speak Common Tongue now, the traditional languages of the kingdoms are real-world languages (Old Atlesean is German, Old Mistralian is Japanese, etc). Atlesean's are also fond of German foods. The kingdoms are not representative of one exact country, as Mistral shows with its elements of both Japan and China.
Fixing RWBY: Nora is a descended of a group of people called the "Fiskare". The Fiskare are influenced by ancient Nordics, particularly vikings. They've long since been absorbed into Mistral however many "pure" Mistralians look down upon those with Fiskare blood.
Echoes of Eternity: Maria's friend Rei is the equivalent of Japanese-American. He's of Sajipean heritage but his family has lived in the United Federation for generations. He's a bit annoyed by his parents for giving him a Sajipean name and feeding him bentos for lunch, because as a kid he ended up beaten up in school.
Create Your Own Fate: The native-born Bajorans draw from a variety of influences, ranging from American "red states" (fairly agrarian, nationalistic, religious, suspicious of the national government) to religious/nationalist extremists in the form of the Circle. There's a particular point made that, unlike the Federation at large, the Bajoran constitution guarantees the right to bear arms (though it's not completely unrestricted: the Bajorans ban depleted uranium ammo for environmental reasons and some locales don't allow open carry).
Several human ethnic groups are introduced to flesh out the setting. Kirovi have a distinct Slavic/Russian flavor, particularly in their naming conventions. The Ralmanni are Romani in origin. There are also the Dromascoi, who were conquered by Lordaeron, and are loosely based off of Romania. However, very little information is given about the Dromascoi.
Shadowprey Village has a Hawaiian feel, surfing and all.
Tauren legends sound like they could have come straight out of Native American oral tradition.
Stromgarde gets something of a German spin, while Dalaran is more French. The Tirasi names tend to sound Italian.
The Dark Irons are apparently inspired by Stalinism. Similarly, the Defias take their cue from Maoists and Jacobins.