Era-Specific Personality

Some characters can have very long careers, and a few stretch all the way back to the silent era. Due to the simple passing of time and countless writers, older shorts can feature characters very different from their later incarnations. Sometimes it's a wardrobe or design difference, but occasionally it's their nature.

Fans will form camps as to which personality is canonical, but some companies (especially Warner Bros.) are famous for treating their characters as actors playing a role. You'll still have fans commenting which incarnation they prefer best. In the case of Looney Tunes characters, this mainly affected those with prolific acting careers -- Bugs Bunny and Daffy Duck were originally the same kind of character, in practice. In that case, differing personalities were based on writers' choices that caught on.

The most obvious example of this idea is seen in 1930s character designs. With only a slight design change (and some White Gloves) Bosko, Felix, Buddy, Oswald, and Mickey look like relatives.

Anime seems to never do this; Art Shift gags usually refer to a completely different style, never an old one. An anime may tweak or simplify designs over the years, but you can guarantee an Osamu Tezuka adaptation is going to loyally stick to the oldschool design.

See also Characterization Marches On, Interpretative Character. If the first version of a character is particularly different from later versions, this can be seen as Early Installment Weirdness.

Comic Books

 * One issue of Superman (Superman: The Man of Steel #37), during the 1994 Crisis Crossover, Zero Hour, had a barrelful of Batmen show up, each based on a particular artist's rendition (e.g., Frank Miller, Neal Adams, Carmine Infantino, Dick Sprang, Bob Kane).
 * A Planetary crossover had them running into various versions of Batman as they shifted between Gotham realities. Batmen they ecountered were, in order - modern Batman, Adam West Batman, Dark Knight Returns Batman, Denny O'Neil Batman, original Batman and future Batman.
 * Superman. Golden Age, he had no problem sending a carload of gangsters to their deaths. Silver Age, he had a no-killing rule that extended to even the most vile of supervillains. And he was kind of a sociopath. Now? Depending on the Writer.
 * Grant Morrison's take on Superman's early years for the "New 52" relaunch is based on the earliest Golden Age character: an anti-establishment radical who appeared in stories like "Superman In The Slums".
 * In the first few issues of X-Men Beast acted just like you would expect from his appearance - rude, rough, slangy, etc. but then they decided it was stupid (he also ended up sounding too much like Ben Grimm) and gave him the personality he has today.
 * Alan Moore's run on the Supreme comic starts this way, with Supreme encountering various iterations of himself stretching back to the 1930s, at least. His arch-nemesis Darius Dax has a similar experience, including an encounter with "edgy Eighties serial killer Dax."

Film

 * James Bond and the world around him change via decade, along with expectations of what a spy character should be like. Naturally, the current version's got a little Jack Bauer Jason Bourne in him.

Live Action TV

 * Doctor Who provides a notable aversion of this trope. Thanks to the regeneration plot device, Time Lords are in fact expected to change their personality whenever they're recast.
 * In fact, for any work of fiction featuring this trope, you can expect at least one person to declare that "such-and-such character is a Time Lord" on the Wild Mass Guessing page.
 * The evolution of Star Trek's Captain Kirk:
 * 1966 - 1979: Nearly infallible paragon, though he will break Starfleet orders if a To Be Lawful or Good conflict arises.
 * 1982 - 1994: More fallible and a bit of a Military Maverick type.
 * 2009 - present: Arrogant young hot shot.
 * Though unlike many of the other examples on this page, this can be explained by the character aging in real time and then having his backstory Cosmic Retconned by a time-traveling villain.

Professional Wrestling

 * WCW once did this when Sting, a veteran wrestler who had drastically changed his look several times over the years, was attacked during a match by a series of assailants, each of whom wore a different-era Sting costume.
 * Another wrestling example might be WSX's Matt Classic, a wrestler who was "in a coma for 40 years" and therefore uses moves, mannerisms, and phrases from 1960s pro wrestling.
 * The Undertaker has had several different "eras" with his persona, such as his original zombie gimmick, his Ministry of Darkness persona, and his biker gimmick.

Videogames

 * In a later self-reference, the "Timeless River" subworld in Kingdom Hearts II takes place in the past, where the Disney Castle counterparts are depicted in their original incarnations (specifically, those of the 1928 short Steamboat Willie). Sora specifically mentions Mickey and Black Pete looking and acting strange.
 * And even the anime-influenced Sora himself is affected designwise, as he wears a simpler version of his first-game outfit and looks more akin to anime art done by Osamu Tezuka in the Timeless River.
 * In Epic Mickey, which way you go on the Karma Meter determines which incarnation of Mickey you play: the scrappy fighter of his original appearances, the straight man of the late 1930s, or the more modern 'hero' Mickey.
 * At least, that's how it was going to be.
 * Kusanagi, a clone of Kyo Kusangai from The King of Fighters 2003, is essentially Kyo's older version from the previous games, as he has Kyo's old appearance, quotes, and movelist.
 * Lara Croft of Tomb Raider has had six wildly different personalities.
 * Sonic the Hedgehog has gotten fan backlash over the years for not quite having the attitude he had back in the 16-bit days, though this is mostly in America where he was marketed that way.
 * Sonic Generations places the Genesis-era Sonic and Dreamcast-era Sonic side-by-side, freely inviting comparisons between the two.
 * Ganon(dorf) existed as a hammy villain up through The Legend of Zelda Ocarina of Time. He has gotten more subtle nuances since then, but whether he is a Tragic Villain or just an Evil Overlord sans ham seems to depend on which timeline we see him in.

Web Original

 * The webcartoon Homestar Runner has an "Old Timey" universe which mirrors 1930s cartoon character designs and personalities.
 * Also, the Chapmans parody their own earlier style: the Strong Bad Email "flashback" parodies the style of the children's book that predates the website, and "lady-ing" parodies the very first Homestar Runner webcartoon.
 * The trope is also used in the Mega Man centric sprite comic Bob and George. The time frame is measured by bittage: 8 bit is the past, 16 bit is the present, and 32 bit is the future.
 * At one point in Marvel/DC After Hours, Superman, Batman, and Spider-Man go back in time to shortly before Marvel Comics was founded. Superman and Batman briefly revert to their Silver Age personalities, which was signified by the use of older action figures. When they revert to their modern personalities, Superman remarks that he'd forgotten how nice Batman used to be.

Western Animation

 * Both Donald Duck and Mickey Mouse were much more mischievous and aggressive in their earlier appearances.
 * Referenced in a Quack Pack episode where Donald Duck was being age-regressed. Instead of getting younger looking, he started reverting to older character designs and became more of a troublemaker (at first; eventually, he actually did become younger-looking.)
 * The Warners from Animaniacs are deliberate throwbacks to 1920s- and 1930s-era designs, per their Backstory.
 * The Batman: The Animated Series episode "Legends of the Dark Knight" featured children speculating about what Batman's really like; their interpretations are pretty much directly lifted from the '60s Batman series (and the '70s cartoons based on it, as well as Dick Sprang's work in the comics), Frank Miller's graphic novel The Dark Knight Returns, and Joel Schumacher's much-maligned "Batman in a tight rubber suit" movies.
 * When Woody Woodpecker was revived in the 1990s, they used the wilder, more irreverent 1940s version, rather than the softer 1950s version that had been used until then.
 * Daffy Duck went from being a wacky trickster to cowardly and non-too-bright to being rather serene and positive, and from there on became cunning and greedy, to be used as foil to Bugs Bunny.
 * Shaggy from Scooby Doo was stripped of all his hippie elements during the 80s, but got them back in the 90s.
 * Velma's also gotten snarkier as time went on.
 * The 90s-and-later incarnations of the franchise are generally more self-aware and willing to play with the series tropes, where the originals played it all straight.
 * When Betty Boop first appeared in the early 30's, she was portrayed as a teenage (sometimes young-adult) flapper-girl with an outgoing personality and loads of sexuality. After the Hays Code of the mid-30's however, Betty was aged up to her mid-twenties, wore long, conservative dresses and became more passive and less wild. However, as she experienced a re-birth in popularity after the 50s, she reverted back to her sexy, Jazz Baby persona in most portrayals and is remembered by these images and behaviours mostly today.
 * Parodied in the episode of The Fairly OddParents "The Crimson Chin meets Mighty Mom and Dyno Dad"- The Crimson Chin has wildly different Era-specific personalities, from 30s pulp-fiction Chin, to edgy 1985 Chin, who got cancelled for swearing.
 * The My Little Pony franchise tends to do this with reoccurring ponies. Most of the characters in the current series My Little Pony: Friendship Is Magic, that were carried over from the earlier G3-series have personalities that are completely different from the ones they had in G3. This is because, while those Friendship is Magic-characters do have the names and color-schemes of characters from G3, their personalities are actually based on characters from G1, the original My Little Pony version from the 1980's. A curious special case is the character of Applejack, a Friendship is Magic character who has the name and color scheme of a G1 pony, but whose personality is completely different from that Pony.