AMC's The Walking Dead evolved so much throughout its run but one thing that remained at its core was that element of building towards a future. No matter what happened, Rick Grimes and his fellow survivors were fighting for a world that their loved ones could survive - and thrive - in. At the top of that list of motivations was Rick's son, Carl Grimes.
Portrayed by Chandler Riggs, Carl was an important part of the TWD Universe throughout its early years. Initially caught in the middle of the Rick/Lori/Shane love triangle as a child, he had to grow up pretty quickly, suffering an immense amount of trauma at a young age - including the loss of his mother, Lori. He would then become a young leader at Alexandria, attempting to recreate and echo Rick's own mission - despite their own personal differences. But it all came to a screeching halt when Carl was shockingly killed off in one of the show's most controversial decisions.
Carl dies in season 8's midseason premiere
Carl died in The Walking Dead season 8 episode 9, titled "Honor". It was the midseason premiere of season 8, which hit its emotional peak in that moment and resulted in the show returning to screens after its winter break on an extremely sombre note. It wasn't the uplifting sense of hope that audiences were craving after what had already been a pretty hopeless double act in seasons 7 and 8.
What's worse is that Carl's journey towards that death started three episodes earlier as he was actually bit by a walker in season 8 episode 6, "The King, The Widow, and Rick". He then revealed that bite to Rick in episode 8 - the midseason finale "How It's Gotta Be" - resulting in that aforementioned midseason break beginning on an equally sombre note. And as fans already knew that there was no way back for Carl, making them wait for his inevitable death wasn't exactly well-received either.
Speaking of Carl's death, here's the exact timeline of what went down.
How Carl's death on The Walking Dead happens
The end of Carl's journey on The Walking Dead begins in season 8 episode 6 when he encounters Siddiq - a survivor that he and his father hadn't come across before. While Rick insists on proceeding forward on their mission, Carl decides to help Siddiq. However, while saving him from an attack from multiple walkers, one of the undead creatures topples over onto him and bites his torso. The show doesn't confirm as much right away, but you can see from Carl's expressions that the unthinkable had happened.
In the midseason finale, Negan and The Saviors come to take Alexandria, but Carl - knowing that he is dying - attempts to negotiate with Negan. He knows that that the villain has a soft spot for him and uses that to outsmart him. Eventually, his symptoms of turning catch up to him and he shows his bite to Rick and Michonne in an incredibly emotional moment that sets the show up for Carl's actual death in the midseason premiere.
"Honor" sees Carl moved to the partially-destroyed church after The Saviors' attack. There, he shares some special moments with Rick and Michonne, telling them both how much he loves them. He gives Judith his hat, telling her that she will beat this world (just like his mom, Lori, told him when Judith was born). He also asked Rick to find a peaceful resolution to the war with the Saviors, which eventually prompts Rick's actions throughout the rest of the season's all-out war.
Then, to spare his family the pain of having to do it themselves - and prevent himself from reanimating into a walker - Carl decides to take actions into his own hands. He dies from a self-inflicted gunshot wound as Rick and Michonne wait outside the church. It's a poignant, heartbreaking moment that signified the end of an era for The Walking Dead - one that many felt should never have happened. And, honestly, they are justified in that belief.
Carl's death did have a lasting impact on the show. Rick eventually changed his approach to the all-out war with the Saviors, defeating Negan without killing him - and even finding a way to save his life after almost going through with his plan to finish him off. He then imprisoned him in the hopes that he could one day redeem himself. Although Rick would eventually be taken by the Civic Republic Military for an eight-year period, Negan would ultimately redeem himself, forming a bond with Judith and vowing to be a better man for her - and for Carl.
Meanwhile, Siddiq became a valuable, important member of the Alexandria community in the five years after Carl's death, serving as the town's doctor. Unfortunately, he would eventually be killed by one of the Whisperers - which fans also criticized for taking away the main reason Carl sacrificed himself.
Regardless of which side of the argument you fall on, you can agree that Carl's death changed The Walking Dead. For better or for worse, the show was suddenly without its endgame because Carl's survival was the main reason that Rick was fighting so hard to ensure everyones' future. Of course, he still had Judith but the show had intentionally placed a huge focus on Carl - and considering the character didn't die in the comics, it's understandable that he got that spotlight on the show.
Unfortunately, somewhere along the lines plans changed and the decision was made to kill the character off. Shortly afterwards, Andrew Lincoln left the show and a time-jump was needed in order to fully reset things. That time-jump obviously wouldn't have happened if Carl was still on the show. And somewhere out there, maybe there's a timeline where we got to see that version of seasons 9, 10, and 11 instead.