Both HBO and NBC (who wanted to turn it into a crime procedural where Rick and Shane would "solve a zombie crime of the week") passed on the show before it was picked up by AMC.
Thomas Jane was originally intended to star when Frank Darabont first pitched the show to AMC, but was already committed to Hung when production began. Jamie Bamber and Stuart Townsed were also attached to the role.
George A. Romero was asked if he wanted to write for the show, but he refused, later calling the show a "soap opera with zombies."
Darabont essentially fired his entire writing staff midway through filming of the season, although AMC claimed that said writers weren't fired (despite production sources indicating otherwise). This may have been a result of cost-cutting measures AMC forced on Darabont (see below).
Robert Kirkman has stated in interviews that he is dissatisfied with the season finale ("TS-19"), and would have nixed the concept altogether if he had greater authorial oversight. He claimed that Darabont was responsible for the episode, and that if he had his way, the season would have ended in a different (and more mysterious) manner altogether.
Jenner's wife Candace was supposed to appear in a flashback in "TS-19," but this ended up getting deleted.
Season 2
Had Frank Darabont not been fired, the second-season premiere (as indicated in preview trailers, leaked information from various sources and deleted scenes in the Season 2 boxset) would have resolved the Vatos plotline introduced in the first season episode of the same name. In the original premiere (titled "Miles Behind Us"), Shane almost gets overtaken by a horde of walkers when his car breaks down after leaving the CDC, and he is saved by Dale and Rick in the RV. With limited options, the group goes to the Vatos camp to warn them that things are much worse than they expected. They find the retirement home overrun (with Guillermo and the rest of the Vatos having been executed by an unknown party), and proceed to take down every walker in the vicinity before hiding inside the home until the morning. The encounter with the horde of walkers on the highway is the only major remnant of the original premiere (as most of the footage was, according to AMC, "unusable"). In total, just 1/3 of the filmed material remained. The Vatos resolution also counts as an Aborted Arc.
There was a series of webisodes planned that were described as "Black Hawk Down-meets-zombies", and would have followed a soldier who encounters several of the main characters while fighting through Atlanta during the initial outbreak. The webseries would have explained the story of the soldier in the tank in the pilot — who, as it turns out, was played by an uncredited Sam Witwer. With Darabont being fired, his plan for this fell through. According to Witwer, there were dozens of other little things like this that Darabont had plans for in the future, but due to cost-cutting measures by AMC (despite his attempts to push the budget down), this never occurred.
Morgan was supposed to reappear in Season 2, but it was delayed due to Lennie James having a busy schedule.
There was initially supposed to be a subplot where Dale kept hearing radio broadcasts from a Christian fundamentalist who the group would encounter during their search for Sophia, but it was deleted.
Originally, Randall was supposed to escape from his restraints and kill Hershel.
Jeffrey DeMunn (Dale) asked to be written out of the show after the situation with Darabont, but had a change of heart and attempted to stay on afterwards. However, AMC refused to budge and had his character killed off near the end of the season. As a result, his storyline and encounter with the Hunters in the comic was transferred over to the character of Bob Stookey.
Among Dale’s deleted subplots would’ve been marrying Andrea like his comic counterpart does.
According to Greg Nicotero, Dale was originally going to encounter Jimmy (instead of a cow) after the latter was attacked by the zombie in the field, which would then attack and critically injure him before he's put down by the group.
The production crew threw around several different concepts for Shane and Rick's final encounter in "Better Angels". There were originally an idea to keep Shane alive and have him appear in the following season, and another (as noted by Glen Mazzara in a Comicbook.com interview) to kill Rick himself(!) and have Shane lead the group. In the end, the powers that be had Rick kill Shane by stabbing him in the chest, then having Carl land the final shot on the zombified man.
Season 3
Had Frank Darabont still been the showrunner at this point, the man responsible for the critically acclaimed films The Shawshank Redemption and The Green Mile would have adapted yet another Prison-based storyline to the screen.
John Hawkes was offered the role of The Governor, but turned it down due to misgivings about taking a part on network TV. Tom Savini was also considered for the role.
Axel's actor revealed that Axel was originally written as a Serial Killer who would kidnap one of the group members after being freed from the prison.
Glen Mazzara has stated that he considered killing Beth instead of Axel in "Home", but decided against it because it would have added too much to the existing storylines and it made for a better shock to kill off the latter character.
Greg Nicotero stated at the 2014 Walker Stalker Con that he tried to pitch an idea to the executives where The Governor would have his throat slit (but survive) at the end of "I Ain't a Judas", as Andrea actually followed through on Carol's advice and attempted to kill him in his sleep. This would have given more of an explanation for why Andrea is kidnapped and put in the torture chair, but the pitch never went ahead.
"Arrow on the Doorpost" was originally titled "Pale Horse," and would have included a scene in which Daryl encountered a headless rider attached to a horse.
Merle's death was decided so late in production that it was only finalized moments before shooting for "This Sorrowful Life" was set to begin. Had he survived, Merle was intended to become a recurring character throughout the fourth season. There were also plans to have a B-plot in the episode that would follow Andrea and Milton attempting to bomb The Governor's apartment, but this was rejected on the grounds of being too ridiculous for the show.
According to extras who appeared in "Welcome to the Tombs", there were many additional scenes of Woodbury soldiers being attacked by Rick and Michonne in the tombs, along with soldiers falling into barbed wire traps placed out by the group beforehand, but these were all deleted from the final print and haven't been seen to date.
Andrea was originally intended to become the leader of Woodbury at the end of Season 3. Instead, she dies, and the townspeople she fought so hard to save are brought to the prison, where they are quickly and unceremoniously rubbed out by the flu and in the immediate fallout from the prison arc, leaving no extant survivors.
Laurie Holden had also signed an eight-year contract and was told that Andrea would eventually become Rick’s love interest just like in the comics, and would last the duration of the series (this all took place before her comic counterpart was killed off, leaving it ambiguous as to whether or not she really would’ve survived the show or at least stuck around to receive her comic death). With her death, Andrea’s place as the Second Love of Rick was given to Michonne, while her comic death would be adapted for not only Lucille in Season 10’s “Here’s Negan”, but also Rosita in the Grand Finale.
According to variousaccounts, the deaths of Andrea/Milton in "Welcome to the Tombs" were intended to be completely different. The episode would have begun with Milton being unexpectedly shot in the stomach in the torture room by The Governor, and left to bleed out while Andrea is still tied up. There would have been more scenes of Milton trying to open the door, along with trying to choke Andrea with a chain in order to spare her from being eaten alive. The subplot was supposed to end with Milton turning, being shown taking a bite out of Andrea's chest, and Tyreese discovering her and shooting Milton. Afterwards, she would ask Tyreese for a gun to kill herself with. The subplot was eventually reshot for the broadcast version, and the only remnant left of the original plan is Tyreese saying to Sasha that he's going to look around in Woodbury.
Season 4
The Mika and Lizzie characters were originally written to be male and female twins, but this was changed after actress Kyla Kenedy's audition impressed the producers so much that they changed the Mika character from a boy (Mike) to a girl.
The director decided that there were too many walkers on the bus in "Inmates", so a number of them were removed. However, some of the cut one included Redshirt Jeanette and several recurring extras, some of whom had been around as long as Woodbury, while those left on the bus were new.
CM Punk was considered to guest star in some capacity during the season but nothing came to pass, though he did guested on a Talking Dead episode (the one for "The Grove") near the end of the season.
Season 5
Early spoilers indicated that a one-legged 17-year-old named Burton would join the group at Terminus. This character became Noah, who breaks his leg (though he doesn't lose it) and joins the group at Grady Memorial Hospital.
A number of the job assignments were cut from the final version of "Remember", namely Abraham joining the construction crew, Rosita meeting Pete to become a medical assistant, Eugene beginning to work on the solar arrays, and Maggie starting as Deanna's assistant.
Aiden Monroe was originally intended to be killed off in "Try", but, as Daniel Bonjour had already cut his honeymoon short to film "Remember," he was killed off an episode early in "Spend" so he could make up the rest of it.
Season 6
It was originally scripted in "No Way Out" for Carl to lose his eye by intentionally jumping in front of Rick and Taking the Bullet, instead of accidentally getting shot by Ron.
Heath was intended to have a larger role, as his comic counterpart is a major supporting character, but Corey Hawkins injured his ankle during filming, and his scenes in "Now" and "Start to Finish" ended up getting cut. Then Hawkins was cast as the lead in 24: Legacy and was Put on a Bus along with Tara (as Alanna Masterson was very pregnant) at the end of "Not Tomorrow Yet."
Averted with the leaked alternate footage that had Maggie as Negan's initial victim, rather than Abraham. The show filmed a death for every single character in the line-up to throw off spoilers in case of a leak due to the fandom’s negative reaction to the Season 6 cliffhanger and being more determined than ever to find out who was Negan’s victim. The footage of Maggie dying is, to date, the only sequence that has ever leaked to the public, the other deaths only being seen in Rick’s hallucinations in the Season 7 premiere.
As Abraham was already decided on for being Negan's first victim, Robert Kirkman and company actually did seriously consider sparing Glenn and discussed several options to do so, but ultimately decided that it would be impossible to do as the character's death was the impetus for so many storylines and Character Development.
"The Well" was originally intended to air as the third episode of the season (and was the third produced), but it was flipped to become the second to air to have a Breather Episode after the dark, violent season premiere.
"The Cell" was originally supposed to feature Dwight, Arat, and several other Saviors getting involved in a car chase with the deserter Gordon. Despite glimpses of this appearing in the Season 7 trailer, the final scene is much more subdued and Dwight goes alone.
The death of Fat Joey in "Hearts Still Beating" was supposed to be more graphic, but in response to the controversy over the brutal season premiere, a Gory Discretion Shot was used instead.
"The Other Side" was originally intended to air as the 13th episode and "Bury Me Here" as the 14th, but their order ended up getting switched.
Micaela Dee auditioned for the role of a zombie in an unidentified episode, but was turned down.
Season 8
Maria Bello was announced to join the cast leading up to the season, but nothing came to pass. The characters heavily attached to her were Alpha and Magna, who are subsequently played by Samantha Morton and Nadia Hilker, respectively.
“Time for After” would’ve featured a sex scene between Eugene and Laura in which they’re just blowing off steam and nothing more. Eugene would’ve been his usual awkward self and would’ve asked to keep his socks on, and his stuffed animal Gremblygunk would’ve been depicted “watching” from a shelf, as a Call-Back to when Eugene himself would spy on Abraham and Rosita having sex in Season 5’s “Self-Help”. The scene was filmed, but cut for being too much of a distraction to the rest of the episode’s plot.
Rick was originally slated to be killed off in Season 8, but plans changed and he is later written out of the main series in Season 9.
As Lennie James is leaving the series after the season, Morgan was considered to be killed-off. However, the writers changed their minds when they realized that Season 1 characters are already dropping like flies in the past year-and-a-half (Glenn in the Season 7 premiere, and both Morales and Carl midway in Season 8).
Season 9
Gregory was originally intended to be killed off later in the season, but his death was moved up to the season premiere.
Maggie and Alden were initially intended to have a romance similar to the Maggie and Dante storyline from the comics. Cohan's departure led to a change of those plans, with Alden instead finding romance with Enid.
Rosita and Eugene were originally planned to get together as they did in the comics, but plans changed and ultimately Gabriel was chosen as Rosita's new lover.
Jesus was only killed off when Tom Payne expressed frustration with the character being Demoted to Extra in comparison to his comic counterpart, indicating that the character was originally going to stick around before ultimately being used as a Sacrificial Lion.
The pike massacre was intended to be the season finale, but Kang felt the show was ready an episode early and would’ve been treading filler if they had waited until then, so it was pushed up to episode 15 out of 16.
Season 10
When talks began for Lauren Cohan to return (at a point after Danai Gurira had already finalized her departure), one plan was for Cohan and Jeffrey Dean Morgan to take over as the leads of the series, which would’ve continued until Season 15. This was also because Norman Reedus was aiming to leave the series around this point. The Walking Dead: Dead City was later formulated instead, and Reedus remained on with the series for its remaining lifespan.
"A Certain Doom" was meant to air the following week after "The Tower", but due to the COVID-19 pandemic lockdowns shutting down post-production, the episode was unable to be completed in time to air. "A Certain Doom" was pushed back to air in October 2020, and would no longer be the season finale as an additional six episodes were announced to fill the gap between Seasons 10 and 11 proper.
The final confrontation with Beta was planned to be longer until Norman Reedus asked to make it much shorter.
Angela Kang indicated that some of the stories told in the extended run would’ve merely taken offscreen during whatever time gap occurred between Seasons 10 and 11 had they not had the opportunity to actually materialize them. This would later be clarified to also refer to the events of “Home Sweet Home” and the group’s fight with the Reaper Montanio.
Dwight and Sherry were to be included in “Here’s Negan” since they appear in the source material, but COVID-19 restrictions plus Austin Amelio and Christine Evangelista’s shooting schedule for Fear prevented them from appearing. Laura was then chosen to replace them as she was also a sympathetic ex-Savior character.
Season 11
Ross Marquand noted that the series was meant to at least run until Season 12. The Reapers were meant to be the villains of Season 11, while the Commonwealth would dominate Season 12 (which would’ve presumably been the actual final season). The pandemic changed things and AMC decided to end the series with Season 11; thus, the Reaper arc only lasts the first part of Season 11 while the Commonwealth spans Parts 2 and 3, the length of a normal season. This explains the rather brief duration of the Reaper arc and Pope’s reign as Big Bad.
“Rendition” would’ve been the debut of Leah, whose romantic relationship with Daryl would then be revealed through flashbacks. However, when Season 10 was given an extended run, the flashbacks were expanded into a whole episode. Angela Kang noted that the creation of “Find Me” worked out better structurally since it gave more time to develop Daryl and Carol’s arc on the side and kept Leah from coming out of nowhere in Season 11.
Maggie’s confrontation with Negan in “What Comes After” was specifically moved up in the timeline from when it happened in the comics to give Maggie closure with Negan prior to Lauren Cohan’s departure from the series, so that if Cohan returned, Maggie’s development and arcs would not revolve around him. By Season 11, plans evidently changed as Maggie’s feud with Negan is a major subplot and the main focus of both characters’ arcs.
The final confrontation with Leah would’ve involved an actual conversation between her and Daryl, but Reedus, much like with what happened to Beta, asked for it to be removed as he felt Daryl would have nothing left to say to her.
Sebastian had a different demise planned at one point, but Kang at the time of “A New Deal”‘s airing refused to elaborate for spoiler reasons. She later clarified that Sebastian would have originally survived until the finale, at which point Pamela would have knowingly sent her son to die in battle, presumably trying to lead the people in fighting the herd that was rampaging through the Commonwealth.
Originally no main character would've perished in the Grand Finale, until Christian Serratos personally volunteered Rosita to be the main casualty of the finale to give it an emotional death and to have closure after having played her character for the better part of a decade.
An earlier draft of the finale had Magna dating someone other than Yumiko after the Time Skip at the end. Nadia Hilker and Eleanor Matsuura strongly objected to this and thus Angela Kang changed her mind.
Angela Kang strongly implied that Daryl and Connie would've made good on their Ship Tease and gotten together, but Lauren Ridloff's leave of absence to film Eternals resulted in Connie having less screen-time than she would've had and the characters don't end the series together.
Annie was supposed to appear in the finale, but scheduling conflicts, COVID-19, and Norman Reedus' on-set injury while shooting the episode prevented it. Instead, it's left to assume that Negan found her again after the battle was over and the two left Alexandria on their own during the time skip.
The original ending of the series would've been a now-adult Judith, R.J., Gracie, Coco, and Hershel driving into Atlanta in a Book Ends shot to the iconic shot from the pilot episode, looking for survivors to bring into their community. R.J. would've broadcasted a message over the radio ending with "this is Rick Grimes", to be answered by a mysterious "Hello?" from an unknown person. Judith's monologues at the start of the 11C episodes were meant to build up to their final message that would close out the series. Though the ending was filmed with new actors to play the children grown up, it was cut due to a different direction and ending being chosen for the series - the sequence that is more or less a teaser trailer for the Rick and Michonne spin-off and thus an ending with the kids as adults would've caused too many timeline and continuity headaches since the franchise was not ending with the show. Instead, the series ends with an epilogue set merely a year after the downfall of Pamela.
midway through filming of the season, although AMC claimed that said writers weren't fired (despite production sources indicating otherwise). This may have been a result of cost-cutting measures AMC forced on Darabont (see below).