Much like Flanderization, The Simpsons has this across the board, with the main character, Homer Simpson, serving as arguably the biggest example within this series:
- Homer Simpson
- Homer's most popular characterization as a crude, clumsy, lazy, ignorant man, with alcoholic tendencies, makes the first season's, "There's No Disgrace Like Home" an extremely odd episode to watch, especially for those who have never seen The Simpsons in its early days. In it, he is embarrassed by his family's boorish behavior, including Marge getting drunk at his boss's party, and takes them to family therapy. If this was written after the first season, the roles would undoubtedly be reversed. Adding to this, Homer sells the TV in order to pay for the therapy — again, something he'd never even contemplate doing post-Season 1. While Homer is somewhat called out on it later that episode, since most of the things he was ashamed of them doing were his fault in the first place, he shows a lot more devotion to his family here than in later seasons.
- Another first season episode, "Homer's Odyssey", has Homer getting fired from his job for crashing a forklift. He goes into such a deep depression at losing the identity of household breadwinner that he actually attempts suicide so he wouldn't feel like a failure around his wife and children. At the end of the episode, he becomes the power plant's safety inspector because he's very concerned that the plant isn't being run safely and wants to make a difference. In later episodes, his on-the-job negligence is legendary, with him personally committing safety violations that would not only get him canned, but probably sent to prison for a long time, if the show cared about realism. He would regularly be sacked for gross incompetence and show little-to-no concern, or casually ditch work for the sake of whatever zany adventure he's going on in the episode. Also, even though his title of safety inspector continues to be mentioned, his job rarely seems to involve any safety inspecting. Admittedly, the plant itself, even without Homer's incompetence, is terribly run and would be shut down in an instant if Burns ever ran into someone he couldn't bribe. Which is probably why Homer has his job security (outside of Burns saying he's here forever after Homer had to beg for the job back when Maggie was conceived); anyone competent would have gotten the place shut down.
- Lisa Simpson falls under this for multiple reasons.
- Throughout the Ullman Shorts and most of the first season, she is a disrespectful troublemaker and not particularly bright, much like her brother. The writers conceived her and Bart as something of an interchangeable duo of bratty kids designed to drive Homer and Marge crazy. As Bart became the show's rascally Breakout Character, however, Lisa as a female version of Bart seemed redundant, so they rewrote her as a brainy, yet socially awkward girl.
- One early short has Lisa refer to Homer by his first name while Bart calls him "Dad." Later episodes would reverse this.
- Lisa, in the early episodes, was a big fan of The Happy Little Elves while Bart preferred to watch Krusty the Klown and The Itchy and Scratchy Show (along with horror movies and, on the episode where Homer steals cable TV, X-rated movies). Later episodes either show both of them being childish, both of them being mature or, in a lot of cases, Bart being the childish one and Lisa being the more mature one.
- Lisa's artistic side arguably dates back the development of the show, since her saxophone solo is part of the opening credits. Another case of this would be her rebellion against her music teacher Mr. Largo. It's part of the opening credits, and is emphasized considerably in a couple early episodes. Later, not only did Lisa avoid conflict with her teachers to the point of becoming a grades-obsessed teacher's pet, but Mr. Largo has been Demoted to Extra (and in some cases, Put on a Bus).
- Early episodes showed Lisa being friends with other average girls in her class, liking ponies, and having small sleepovers at her house. The later episodes established her as a sad loner who is very disliked, has little to no friends, is constantly bullied for being "smart", a very uppity Granola Girl, and always trying to find friends outside her school and joins environmental groups and MENSA.
- Supporting characters have gone through this too. When we first see Principal Skinner's mother in "The Crepes of Wrath", she is the stereotypically sweet, frail old lady who embarrasses her son by calling him "Spanky." Afterwards, she was rewritten into a cruel matriarch who controls every aspect of her son's life. This could have had something to do with the cherry bomb incident in that episode though.
- Skinner himself has changed. Whereas now he's a pathetic mama's boy who is usually easily outsmarted by Bart, in the early seasons, he was far more competent and authoritative, and his main shtick was a tendency to mispronounce long words (one of which was his own surname), have flashbacks about his days as a Vietnam War soldier and demonstrate his Green Beret skills, such as taking out a group of lawyers from The Disney Corporation who threatened to sue Skinner over using "The Happiest Place on Earth" for the school carnival. The writers kept the 'Nam flashbacks (though those got phased out as well as time went on), but ditched his penchant for mispronouncing long words, and eventually made him a loser who always fell for Bart's tricks. Accordingly, his relationship with Bart has gone from Worthy Opponent levels of respect to simple contempt from Bart. He also was revealed in an infamous episode to have been an Armenian-American juvenile delinquent in the Sixties who only reluctantly goes to Vietnam and then steals the identity of the real Seymour Skinner, who was believed killed. This "origin" went over so poorly with fans that it was almost never mentioned again, even in-universe.
- Dr. Hibbert, in his first appearance, "Bart the Daredevil", is as a stern, competent professional. By his very next appearance, he became somewhat absent-minded and laugh-prone ("Ah-hee-hee-hee!") and an Expy of Bill Cosby, complete with a wife who looks like Phylicia Rashad (only with darker skin), a teenage son who looks like Malcolm-Jamal Warner, and a daughter who looked like Keisha Knight-Pulliam.
- Police Chief Wiggum also went through a dramatic shift. In early episodes he is portrayed as a serious, no-nonsense police officer surrounded by idiotic officers (though still with the smarmy voice). Later on, he becomes an idiotic police officer, whilst the others (especially Lou, who is now the Cloudcuckoolander's Minder) become somewhat smarter.
- His son Ralph varied widely in personality over his very scant appearances (being essentially a Living Prop) up until his starring role in "I Love Lisa", which also showed a very different version of Ralph. The Ralph in that episode is shown to be pretty dumb, but more in the below-average-for-an-eight-year-old range, and showcases some actual genuine emotions (he's very much aware of his status as an unpopular kid, for instance, and a decent actor). Later appearances by him focus more on the dumb things he says, and a couple seasons later, he'd more or less solidified as a Talkative Loon who is dumber than a rock and whose dialogue tends to have little connection to reality.
- Even before Ned Flanders became the Trope Namer for Flanderization, his personality had drifted towards being nice and meek. It's sort of funny to watch his first appearance, where he's so indifferent/oblivious to Homer's obvious financial problems that it reaches Jerkass proportions and he actually seems fully deserving of Homer's enmity.
- Nelson and the Jimbo, Dolph, and Kearney trio used to scare Bart and were, overall, much worse kids. In fact, Nelson, in his first appearance, is so menacing that Bart has to use military tactics against him. He was also depicted — at least in Bart's imagination — as a complete sadist, not only killing Bart but punching his corpse at the funeral. Now they're all Bart's pals, with Nelson practically being one of the gang. That's not to say Nelson and the trio don't beat Bart up every now and then.
- Kearney himself is Older Than They Look, being in his 30s but having been held back repeatedly to the point where he's still an elementary student. In an early episode he, Jimbo, and Dolph had to use fake IDs to buy alcohol, while future episodes have Kearney drinking due to his age.
- "One Fish, Two Fish, Blowfish, Blue Fish" features some supporting characters behaving in ways that seem extremely out of character in hindsight but were undeveloped or underdeveloped at the time. It features Lou and Eddie acting as incompetent or malicious policemen when generally speaking later on in the series they are portrayed as more reasonable, competent foils to their boss, Chief Wiggum. Additionally, Smithers sees Mr. Burns eyeing a beautiful woman and not only doesn't get jealous, but also encourages him and seems to be interested in the woman himself.
- In the very first Ullman short, Bart asks Homer about the mind, a deep philosophical inquiry more apt coming from Lisa and that seems unimaginable of crossing Bart's mind, even in the later shorts.
- In early episodes, Krusty the Clown sometimes seemed to be a bit half-assed, but he still clearly cared about the quality of his show and the children's happiness. Starting around "Like Father Like Clown", he became much lazier and more self-absorbed, and came to care little about what was in his show as long as he got paid for it. Moreover, the joke of Krusty being illiterate was dropped after only a few episodes.
- In Lionel Hutz's first appearance in "Bart Gets Hit by a Car", he was shown as fairly competent in his Ambulance Chaser ways, if quirky and amoral, coming within spitting distance of a million-dollar payout until Marge proved to be a Spanner in the Works. In his later appearances, he tends to be hopelessly incompetent at law and usually either fails his cases miserably, has his clients bail him out, or succeeds by pure luck.
- In the first two seasons, the joke with Kent Brockman was largely related to his pride about being an Emmy winner and his clearly artificial and uncaring attitude towards the subjects he conveys. Starting around late Season 2/early Season 3, much more emphasis is put on his unprofessional attitudes and his rather bizarre or disturbing takes on current events (not that his earlier focuses were totally eliminated, though they were substantially toned down).
- In the Season 1 episode "There's No Disgrace Like Home", Homer mentions that his mother always considered him a huge disappointment, implying she was just as verbally and emotionally abusive as Abe. Later episodes show that Mona Simpson is far from being the abusive parent she was implied to be in said episode; she is a sweet, caring woman who loves Homer more than anything in the world and who was forced to go into hiding and abandon her son because of Mr. Burns.
