This entry is trivia, which is cool and all, but not a trope. On a work, it goes on the Trivia tab.
Fountain of Expies aka: Iconic Characters
"And there's a million of us just like me Who cuss like me; who just don't give a fuck like me Who dress like me; Who walk, talk, and act like me And just might be the next best thing, But not quite me!"
A character who is so popular and impactful that many other characters created afterwards are heavily inspired by it. They share even more than its Character Archetypes, they are its expies basically the same old character recycled, with some minor changes, to make it fit into the new setting. The original one gives inspiration not just for their basic Characterization Tropes, but for parts of their relationship dynamics, personality, and appearance.
While too many authors using the same obvious expies could be considered a worrying trend in terms of originality, it isn't an inherently bad thing. As a longer time passes, creators might be more and more likely to make bigger changes to the character, eventually growing it into a whole new Character Archetype trope on its own. In other cases, it's possible that the resulting characters are too different even for that: Talented writers can explore certain aspects of a character with an expy, and other aspects with another expy, in a way, that if you would compare the two expies, they wouldn't even appear that similar to each other. While it's possible that a Fountain of Expies also serves as a Trope Codifier for the character's most fundamental tropes, other times the shared similarities are more vague.
In the following "subtropes" list, only add trope pages whose descriptions are explicitly based on the idea of collecting characters that are based on a first one. There are other tropes that were more indirectly started or codified by certain characters, but these should only be referenced in the second, character-based listing.
A subcase of Follow the Leader.
Though Fountain of Expies is not a trope, it does have Sub Tropes. These are:
Captain Harlock is very iconic in Space Opera anime, and he shows up damn near everywhere in anything where there are huge spacey battleships. Notable Harlock expies include Alex Row, stoic renegade captain of the legendary steampunk battleship "Kill'em All" Silvana, and the villainous Vicious, who even has the weird bird, probably to make up for his distinct lack of a battleship.
Then Heero himself is thrown into the mix as well. Former child soldiers who can keep the military aspect of Real Robot shows while still being young enough to appeal to kids and/or teenagers. Such expies include Setsuna F. Seiei and Sousuke Sagara.
Guts also have some characters based off of him like Kirito who is called the Black Swordsman who is dressed in black and gets a BFS later and The Dragonslayer who wears a similar armor to Guts's Berserker Armr.Although he turns out to just be a Suit of Armor and The Protagonist is much of a Guts Expy when wearing The Armor and fighting fate.
Being one of the most iconic anime characters ever, this obviously happened to Astro Boy. There have been numerous stories about humanoid robots that rely heavily on the series. The American Robot Boy and My Life as a Teenage Robot come to mind, along with the Japanese Jetter Mars and Mega Man.
While Superman could be said to be the Trope Codifier for the whole Super Hero genre, he is even more directly the inspiration for every single Cape superhero in terms of personality and outfit, and for anyone with the standard Flying Brick powers (including the aforementioned Goku!).
Captain America is the best known patriotic superhero, and as such has inspired numerous Expies. Among them are the Fighting American, the Guardian (also created by Joe Simon and Jack Kirby), Agent Liberty, General Glory from the JLI, and Commander Steel.
Almost without exception, if a work is intended as a parody of/meditation on/deconstruction of/homage to the idea of superheroes in general, there WILL be a Justice League of Expies and/or an expy Fantastic Four.
The creatures in the Alien series inspired countless other alien monsters with elongated heads, rows of fangs, and an overall nightmarish appearance, especially common in video games.
Godzilla, the quintessential city wrecking giant monster, has had too many monsters based on him. You can say "Godzilla-sized" and everyone will know what you're talking about. See Kaiju and Rent-a-Zilla for examples of Godzilla clones.
Sherlock Holmes. The inspiration for hundreds of eccentric private detectives in all kinds of settings, many of them explicit expies, to the extent that from the time he became popular until Trent's Last Casedeconstructed the type in 1913, it was well-nigh impossible to find a Great Detective who didn't rip him off, or, for that matter, a crime-solver who wasn't at least a parody of a Great Detective. Several characters inspired by Holmes have become distinctive popular characters in their own right, including Gregory House and Batman. Though Holmes himself is an Expy of Edgar Allan Poe's Auguste Dupin (by Conan Doyle's own admission), so Dupin could be said to be the true source.
James Bond is possibly the most famous depiction of a spy and is copied endlessly. His villains have also had a big influence on fictional characters, with Ernst Stavro Blofeld being quite possibly the most commonly copied.
Son Wukong: In addition to many Chinese adaptations and knock-offs, the immortality-seeking monkey king with an extensible staff and great magical powers is known to the Japanese as Son Goku.
In Visual Kei there are a lot of artists that get this treatment, but probably the most notorious is hide. The amount of hide clones or one-time hide clones within Visual Kei is enough to fill an entire page, but some of the more well known are Die and Kaoru of Dir En Grey (though they currently are not), Jun of Spiv States plus the entire band concept of Spiv States being a thinly veiled copy of hide's solo band, and a 2013 photoshoot for a band called CELL featuring everyone in the band as a hide clone. It's been overdone to the point that anyone in Visual Kei with red or pink hair, especially paired with hide's face or eye makeup, is a clone of him regardless of sound or instrument.
That "control other player" part sounds morbidly familiar...
These characters, derisively called "Sephiroth Clones", are becoming increasingly common, especially in later Final Fantasy games. On any given Final Fantasy XI server, you will find dozens. All of them Elvaan males, all with long silver hair, almost always Samurai.
Excepting minor cases of characters who are Expies of non-Star Wars characters (the Imperial Agent is a dead ringer for James Bond) and of earlier BioWare characters (Kaliyo is Jack).
If a video game produced after 2001 has a main character who's head to toe in Powered Armor and has any sort of personality, you can bet that said personality will resemble Samus Aran and/or the Master Chief, as will the abilities and limitations of said Powered Armor.
There will always be gameplay expies of Mario. The main characters of which will be expies of Sonic, either in design or personality.
When the Twin Blades power set was added to City of Heroes, thousands of clones of the aforementioned Drizzt Do'Urden were the first characters seen using it. Drizzt's popularity as an overused character even extended to video games...
When the first expansion for World of Warcraft hit, giving the Horde blond elves, in the first hours there were literally thousands of variations of Legolas, most of them hunters with bows, as well as hundreds of Sephiroths.
Back in the early 1930s, every new cartoon character that came along was a Mickey Mouse clone. Ironically, Mickey himself was merely following the formula established the decade before by Felix the Cat, and more than one person has stated that he was merely Disney's previous star Oswald the Lucky Rabbit with round ears and a long tail.
Some people theorize that the whole "black skin, white mouth" genre of funny animals started out as an animated version of minstrel shows.
Felix's ability to spawn expies even extended past animation. Sonic the Hedgehog looked more or less exactly like Felix in the Genesis era, which kickstarted a bunch of expies in video games, though almost none besides Sonic himself remain.