A Period Fic usually takes the characters of any fandom and places them in a different time period than the setting of the story. It may involve time travel, but most of the time it doesn't.
May or may not include the Used Future.
- Scion: The Last Aeromancer is a story on FanFiction.Net which turns Avatar: The Last Airbender into a Western fantasy while keeping the plot mostly intact. However, the author hasn't updated for a very long time, so it's sadly a Dead Fic.
- The Animorphs fic What if they were all pirates? is Exactly What It Says on the Tin.
- Batman 1939 explores Batman's fight to clean up Gotham during World War II. While Batman himself was around in 1939, the fic includes characters and concepts that were not part of the Batman mythos in The Golden Age of Comic Books.
- Marvel Cinematic Universe
- There is a minor genre of Captain America: The First Avenger fanfic where various characters (almost always just one to limit familiar elements for them to latch onto) from the modern day get zapped back in time to the early 1940s, usually either Brooklyn or London, just in time to serve in World War II with Steve, Bucky, and the Howling Commandos. Darcy Lewis and Tony Stark are popular choices, as seen in Bygone and Time Falls Away, respectively, as well as Clint Barton in The Other Man Out of Time, Natasha Romanoff in Just a Blast From the Past, and a post-Winter Soldier Bucky who has joined the Avengers and swaps places with himself circa-1944 in to memory now i can't recall. There's even a handful of crossovers that do this, such as Edward Elric (well, a genderbent version) in I'll Catch a Break Someday, and even Hermione Granger in Three of Fate. Bonus points if there's a sequel where the timeshifted character gets back to the present to see Steve get defrosted, and the aftermath of Steve seeing his friend (or lover) in the future not a day older since 1945.
- The Guilded Age is a retelling of The Avengers (2012)... if it was set during the late Victorian era. It's notable among other historical AUs in MCU fic for adapting a storyline that necessitates superpowers and everyone's ability sets rather than simply a no-powers AU romance or character drama. Captain America is a defrosted Napoleonic-era naval hero, Iron Man has a Steampunk look, and the Hulk still managed to be a thing, albeit without the help of gamma rays.
- The AlternateHistory.com fic Superman 1842: Spirit Made Fleshnote transplants the DC heroes into the 19th century. Kal-El lands in the Great Plains, and is adopted by a Native American tribe (and turns out to be a massive help in resisting settlers and the US government). Bruce Wayne is a Métis boy, son of Thomas Wayne, a wealthy fur trader. Aquaman is adopted from a freak show...by a slaveowning Southern planter. Meanwhile, Lex Luthor grows up as an Irish-American orphan in New York City, whose friend becomes The Flash. At present, none of them have met each other yet (though Aquaman did meet Vixen, and fought her over the ethics of slavery). Sadly, as the fic appears to be abandoned, they likely never will.
- The Doctor Who fanfic collection Really Stretching UNIT Dating has stories placing the Brigadier and UNIT in the 1790s, 1920s, 2020s, Ancient Greece and 12th century.
- Horatio Hornblower takes place in the Age of Sail era, and the TV adaptation is specifically set in the French Revolutionary Wars and the Napoleonic Wars. Half Jack is an AU fic from World War I. It starts in 1915, roughly alongside the Battle of Loos and after Dogger Bank. Horatio and Archie are Sub-Lieutenants instead of midshipmen.
- In universe, Twilight Sparkle's Secret Shipfic Folder has "Hearthswarming: A Detailed Account".
- NGE: A Century Apart asks the question, "What would happen if Neon Genesis Evangelion took place 100 years earlier than it did in canon?"
- Golden Day by Gondolier moves the plot of The Phantom of the Opera to Hollywood in the Roaring Twenties — with good period research, no less.
- Rendezvous With Fate by iCe relocates Ranma ½ to feudal Japan, and casts Akane as the time-traveling widow of Ryouga, who has accidentally come back in time and possessed the body of Ranma's estranged wife, Kodachi.
- Matrose Mond by David H. Olivier sets the action of Sailor Moon in Nazi Germany.
- Blood of Beauty takes Sonic the Hedgehog into 1880s American, turns several characters into vampires, and dabs in Paranormal Romance.
- There was once a sudden explosion of Cartman/Kyle South Park fics set in Nazi Germany, with Kyle in a concentration camp, hiding in Stan's family's attic, or otherwise persecuted, and Cartman as a sadistic Hitler Youth.
- The Rod Squad is basically Chip 'n Dale: Rescue Rangers, but ten years earlier, in 1979. Chip wears a tie that's as wide as a surfboard (and he uses it as a surfboard), Dale has an afro, and Gadget wears bell-bottoms and platform shoes. Together, they have to face a lot of "HASSLES" and "RIP-OFFS" on their assignment by baseball manager Charles O. Finley to prevent a Disco Demolition Night.