There is an interesting phenomenon that happens in many comic book series in which a character who had been published for decades by Marvel and DC had been replaced back in the 80s or early 90s. Their replacements were naturally viewed as Replacement Scrappies for a while, but aren't any longer. But now (in the 2010s) the original character is being brought back (usually because the now-middle-aged fans of the original character are Running the Asylum), and are being considered Replacement Scrappies because an entire generation of "new" readers and fans, most of whom weren't even born yet when the original character was replaced, have grown up enjoying the adventures of the new character and aren't all that enormored (or in some cases, even interested) in the "old guy" and don't like "their" character being replaced like that.
Spider-Man: Don't forget Ben Reilly who was disliked for no other reason but that he wasn't Peter Parker. (That, and appearing in the story which caused severe Ending Fatigue.)
Reilly was hated mostly because of the revelation that he was the "real Peter Parker" and that the Peter fans had been reading for twenty years was really a clone. After the huge fan outrage Marvel quickly backtracked and reversed that decision.
Kaine, another Spider-Man clone, was a less explicit form of this trope. He wasn't really a replacement villain for an old one, but his Bridge Drop of Doc Ock solidified him in fans minds as an unwanted loser who was biting off more than he deserved to chew in casually offing a beloved, classic Spidey villain with decades of continuity to back him up, and prompted cries for Doc Ock's resurrection and Kaine's axing. Basically, Kaine managed to become a Replacement Scrappy for a character whose role he wasn't even taking over.
Also, as pointed out in the Spider-Man Wild Mass Guessing page, all of her Informed Attributescome from other love interests like Mary Jane, Black Cat, and Deb Whitman. Now people are hoping she'll "be like Gwen Stacy" and die.
Following the events of Spider Island, Peter and Carlie broke up. However, Carlie is not completely out of the picture and remains friends with Mary Jane, as well as serving as Spidey's occasional ally on the police force.
The new Hobgoblin is considered to be this by many fans, especially since he killed off the original Hobgoblin, a fan favorite, after the latter character returned after a decade of anticipation.
Fortunatly, it turns out the original Hobgoblin was alive and well all along, and became the focus of a major 2012 storyline where he confronts the pretender.
Doctor Octopus has become a major one among fans after a recent arc concluded with him taking over Peter's body and becoming the new Spider-man, while Peter dies in his, leading up to the new series Superior Spider-Man. This cooled off considerably once it was revealed that both their minds were in Peter's body. ..... Only to flare up again when Otto erased Peter from his mind and took full control.
Happened to Nightwing in JLA-Task Force. He wasn't loathed by the fans, he was loathed by his team members in canon.
During Grant Morrison's JLA run Huntress is that to Batman (she was brought in as a last second replacement for Connor Hawke. He eventually kicks her out after her continued disregard for rules leads to her almost executing a defeated villain.
And since we brought him up, this happened to Green Arrow Connor Hawke. Even though fans had warmed up to him, many writers would treat him poorly as he wasn't Ollie. For example, he was given a disease that prevented him from holding a bow again, something that seemed to even irritate people who weren't fans of the character. Currently in the New 52he doesn't even exist, and probably never will.
Hawkgirl Kendra Saunders is an interesting case. Fans generally seemed to accept her and didn't mind so much that she wasn't truly Shiera. They had the same soul, after all. However quite a good number of fans were irritated when Shiera was revived in Blackest Knight and Kendra was set up as the Hawkgirl of Earth 2.
This may have been a factor in the failure of Robert Kirkman's very well-written Irredeemable Ant-Man series. Insofar as Ant-Man has fans (every character is someone's favorite, right?), they would presumably be fans of Hank Pym, the original Ant-Man, or Scott Lang, the second to use the name; Irredeemable was about a third, brand-new character, Eric O'Grady. It didn't help that Eric O'Grady was an unlikeable dick
The funny thing though is that O'Grady only exists BECAUSE Sony has the rights to make Ant Man into a movie and has stated that not only do they want a family friendly film out of the character but were going with the Scott Lang character with Hank Pym as his mentor. So of course, Marvel creates a new Ant Man who's a soulless asshole of epic proportions and shove it at readers, many of which are STILL bitter as hell that Bendis was allowed to kill Scott Lang off to begin with, in such a cheap and petty manner that he did.
The Sandman: When Daniel replaces Morpheus near the end, this reaction is inevitable and instinctive for readers and characters alike. spoiler:The shock is gently muted as the final arc deals with the other characters - notably the raven, Matthew - coming to terms with the replacement. This openness, combined with Daniel's dignified humility and the knowledge that he had been carefully hand-picked by his predecessor, helps the reader to accept him.
It probably helps that the series ends at this point, since one of Daniel's positive qualities is the absence of some of the original character's inner turmoil. He is an easier character to like, and we never really see him in action enough to compare how he drives the plot.
It's much easier to accept if you came to the series after its completion and know that it is essentially about the downfall of Morpheus.
There are a lot of fans who hate any character in Runaways who took the spotlight after Gert died. No one gets this more than Klara Prast, for being the only character not created by Brian K Vaughan, for not having a supervillain parent like every other member of the team, for being introduced in a story generally regarded as a Bizarro Episode, for freaking out over the team lesbians, for not having an origin for her powers, for having a punny name...
Lampshaded, when Molly remarks that the team eventually gets used to the new recruits by the time someone else dies.
The Flash has had issues with this very similar to Green Lantern mentioned above. At the end of Crisis on Infinite Earths, Barry Allen made a Heroic Sacrifice, and Wally West, then the Kid Flash, became the Flash. Wally was not well received at first, whether due to his being young, a Jerkass, or the fact that he was less powerful (he lost a lot of his speed during the Crisis and didn't get it back for years.) While Wally grew into the role and gained acceptance, Barry kept appearing in one-off stories set in the past, time travel stories and one notable "fake out" event as well as a short lived TV series keeping his fandom alive. When Barry came back after 24 years of being dead, fans are split.
But when Bart Allen had his turn as The Flash, fans were much more in agreement about their loathing of the character due partly to the Wangst, partly due to his being artificially aged to shoehorn him into the role, but mostly because the character lost his Fun Personified sense of humor and cheerful demeanor.
Barry is getting this more now than ever since in the New 52 Wally was not only never Flash, but never even Kid Flash. Even fans that don't like Wally seem to feel that this was a low blow to his fanbase.
Many people dislike Jason Rusch (Firestorm), and Ryan Choi (The Atom) due to the killing off or running off of their predecessors. However, when Ryan Choi was ignominiously killed off, people had gotten over that he wasn't Ray Palmer, and now viewed Ray as this. After a pretty massive racial controversy that got coverage on some non-comic sites, DC retconned Ryan's death during the Flashpoint series and now he is the sole Atom in the New 52 continuity, with Ray being regulated to a scientific adviser for the S.H.A.D.E. organization.
An odd in-universe form of the Replacement Scrappy status of Ryan Choi came in Dwayne McDuffie's Justice League of America run, where Batman, Superman, and Wonder Woman considered asking him to join. Superman is reluctant on the subject, saying that he doesn't want to replace Ray and would prefer to keep the position of the Justice League's Atom open in case he came back.
The New 52 continuity not only retconned the death of Ronnie Raymond (the first Firestorm who was killed to make way for Jason) but now made it possible for both he and Jason to become Firestorm at the same time, alleviating some of the tension between the characters' respective fanbases.
Holly Granger (as the second (or third?) person to bear the title of "Hawk") also got this reception by fans, though it didn't help matters that writers had no clue what kind of personality she had, or bothered to flesh out a personality or backstory for her to begin with. Being retconned in as "only child" Dawn Granger's sister and an usurper of Hank Hall's Hawk powers only rubbed the salt in further for her hatedom. They rejoiced as Hank Hall was eventually brought back to life while Holly was killed off, and she appears to no longer exist at all in the New 52 continuity.
When Marvel Comics bought out Malibu, they cancelled several titles and rebooted many others. Mantra was originally a title about a male warrior reincarnated in the body of female mystic and his struggle to cope with his new role. When Marvel took over, the central character was Put on a Bus by being banished to another dimension and the Mantra mantle was passed to minor background character; a teenaged girl who had appeared as a babysitter in a couple of issues. Needless to say, fans were not impressed. In fact, this seems to be the consensus reaction to everything Marvel did to the imprint.
In-universe, Jakeem Thunder was seen as this by a number of the original Justice Society of America members. Ironically, he never really received much negative treatment from the fans since his predecessor wasn't a character most readers were likely to be familiar with in the first place.
When Acclaim bought Valiant Comics, they did this to every main character save Turok, who got more popular because now he was fighting cyborg dinosaurs. Then Acclaim went broke and the whole thing was tossed aside anyway, but by then it was a mercy killing.
Feral, the angstygoth in Strontium Dog. He wasn't a bad character in and of himself, but the fact that he replaced Johnny as the protagonist meant he was doomed from the start.
Averted with Captain America. When Cap's old sidekick Bucky took the mantle after Steve Rogers' death, his portrayal was done successfully and he was widely accepted by the fans. To the point where Steve Rogers' inevitable return disappointed many fans that had grew accustomed to Bucky Cap! Possibly because of this, even after Rogers came back, he declined to take up his shield again and let Bucky continue to be Captain America for a while.
Batwoman was (and still is in some fans' minds) seen as one of these after she took over the lead female Bat Family role from the Cassandra Cain incarnation of Batgirl, who was moved out of focus. This was largely erased after she starred in a well-recieved, Eisner Award run of Detective Comics.
The fourth Batgirl (Stephanie Brown, formerly Spoiler) has been seen as this as well, due to her being a blonde Caucasian female who replaced one of the few Asian superheroes in all of comicdom (and the only female Asian hero to maintain a long-running solo series). (Oddly enough, Cassandra and Stephanie were Les Yay-riffic best friends in-universe and would probably take offense at this.) Steph would eventually win over a a number fans by being a really fun character. Though her book wasn't a smash hit (it had enough sales to be in the top hundred comics being sold, but not on par with usual Bat-books), she managed to win over a very vocal fanbase that protested heavily once she was removed from the role.
Both Stephanie and Charlotte Gage-Radcliffe (who later took on the identity of Misfit) both dealt with this from Oracle when they first attempted to take on the Batgirl mantle, with Oracle even slapping Charlie after she made a disrespectful remark about Cassandra.
The second Wonder Girl (Cassandra Sandsmark) is hated by some of the more diehard Donna Troy fans. Some even wish that she weren't a "blonde, white girl" so that she would be killed off easier for Donna to go back to the role. This is especially irritating since in the 90s, Cassandra was a much more friendly, likable character then the Scrappy people see now. Further made worse for Donna's fans in the New 52 continuity, where Cassie's new connection to Wonder Womannote Cassie is Diana's niece, the daughter of Diana's half-brother Lennox hasn't been revealed in-universe despite the relaunch being nearly three years old now.
Her popularity decreased however, as Peter David was allowed to completely revamp the character in his own run on Supergirl. His Supergirl was actually an angel, created when the Matrix Supergirl fused with a human named Linda Danvers. His run, while making a number of references to the original Supergirl, touched on religious and supernatural themes. It was seen by many as a departure from the original character and the Superman mythos (although it's not like Superman hasn't dealt with magic and demons before). The situation was similar to the Cassandra Cain Batgirl (see above) in that despite her earlier problems Linda gained a sizable fanbase and the series ran for several years. Peter David finished the series with an arc that reintroduced the original Supergirl with the hope of turning it into a new series. Unfortunately it didn't happen and Linda was Put on a Bus, but it may have inspired the creation of the Supergirl that came after the next one...
And finally a new version of the original Supergirl, Kara Zor-El, was created supposedly just to get rid of the confusing origins of the previous Supergirls now that the Legacy Implosion policy was overturned. Although her initial appearances were promising (except for people who were upset with Linda's disappearance), she garnished significant hatred for being both Darker and Edgier and Ms. Fanservice. Not to mention the fact that her backstory on Krypton was Retconed with every writer she had. An Author's Saving Throw finally softened her character and clarified her history, which was mostly accepted by the fanbase.
At the same time as the Death of Superman arc, Batman also got a Replacement Scrappy in Azrael, who took up the mantle after Batman's back was broken. He went over terribly with the fans, but like Superman, the writers never intended, and the readers never believed, that Azrael would ever be a permanent replacement.
Like with the Bucky example above, averted entirely when Dick Grayson became Batman. The decision for both Bruce and Dick to act as Batman simultaneously is seen s a welcome third option. Some fans really didn't want him returning to his role of Nightwing.
Tanarus, the guy who's replaced Thor after Fear Itself is got hate immediately, because he looks like a Nineties Anti-Hero, his appearance and Thor's death mean that there won't be interaction between Thor and Kid!Loki for awhile, he's not using Mjolnir at all, but a weird staff with a heavy head (indicating to fans that he's not worthy to be Thor anyways, since a worthy person can lift the hammer), and for not being one of the many established people who could take over for Thor, namely Beta-Ray Bill and Thunderstrike. Oh, and the fact that when the announcement was made Thor wasn't even dead yet.
The first and last seem to be annoying people the most, since the first is clearly so Kid!Loki will have a harder time of it without Thor to protect him and the latter is seen as being too much like the DC reboot's treatment of well-liked characters.
In-universe, Loki loathes Taranus for this very reason. It's even worse for Loki because he's the one responsible for this situation.
Thankfully, this turned out to be wholly intentional on the writer's part, as Tanarus was revealed to be someone impersonation Thor who had usurped everyone but Loki's memories of him, and ended up integral to Thor's return. Notably, he really didn't star in most of the comics, Loki taking over that title too until Thor was back.
The new Ultimate Spider-Man, Miles Morales, was initially treated like this in-universe. A number of characters such as Nick Fury and Spider Woman felt it was disrespectful of Miles to don the Spider-Man mantle after the death of Peter Parker, but he managed to win both of them over after displaying his heroism during a battle with Electro. However he still routinely deals with cops and civilians who view his actions as disrespectful to Peter's memory.
Not like it didn't happen out of universe as well, however. Due to being an African American, Miles is polarising. Many who defend him will accuse others of being racist, but there are some who do hate him out of racism and many who like him for being a generally nice kid trying to do good. But, other critiques of him (like being too similar to Peter meaning that the replacement was unneeded, the fact he was created for no other reason than to be Black Spider-Man comes off as making a Token Minority Spider-Man, and some aspects of his background are seen as racially stereotypical) have been ignored due to this, and along with those who hate him for being a Replacement Scrappy, tend to be labelled as racists despite not caring about his race.
This can happen for whole teams as well. After the original Gen 13 ended with the team being killed with a nuclear bomb, the book was releaunched with an all-new team created by Chris Claremont. The combination of the heavy-handed, editor-mandated deaths of the old team and the Five-Token Band nature of the replacements meant that the results were pretty unpopular. The "new" Gen13 was cancelled after 16 issues, ending with the original team being bought back to life. The "new" Gen 13 have never even been mentioned again.