Carl is Lori and Rick Grimes' son and Judith's elder brother. Upon learning of his father's shooting days before the outbreak, he is devastated. When the outbreak begins, Shane and Lori take him to the supposed safe zone in Atlanta. On the way there, he is told that his father is dead, and he gradually began to accept it. In season one, after they set up camp with other survivors on the outskirts of Atlanta, Carl begins to look at Shane as a father figure, as he does various activities with him such as fishing. Carl appears to be oblivious to Shane and Lori's ongoing sexual relationship. When Rick returns, Carl is overjoyed and Lori restricts Carl's interactions with Shane. After walkers overrun the campsite, killing and injuring many quarry survivors, Carl and the group travel to the CDC, where they enjoy the facility's amenities. Following the CDC's destruction, they start traveling again.[7]

In season 2, Carl is shown to be yearning for more responsibility within the group, such as helping to scavenge for supplies. While searching for the missing Sophia, he is shot and wounded by a man namedOtis, who leads them to a nearby farm.The owner, Hershel Greene, operates and saves his life. While in recovery, he begins to develop a colder mindset, which worries Lori. This new mindset continues to develop following the reveal of Sophia as a walker. He denies the idea of heaven and shows disrespect towards his elders. In the season's penultimate episode, Carl saves his father by shooting Shane, who had become a walker. His gunshot attracts a horde of walkers and so the group is ultimately driven off the farm.

In season 3, six to seven months later, Carl has evolved into a child soldier of sorts; he has grown more proficient with weapons, and has adapted a more mature demeanor, as well as a more responsible role within the group. He has grown distant from Lori and shows a developing crush on Hershel's seventeen-year-old daughter, Beth. After watching his mother die while giving birth via C-section, a distraught Carl shoots her per her request to prevent reanimation. While Rick, Oscar, Daryl and Michonne head out to attack Woodbury, Carl is left in charge of protecting the others inside of the prison. Upon the arrival of Tyreese's group, he takes the initiative to lock them all out of his cell block. In the finale, Carl kills a teenage member of The Governor's army, who failed to drop his gun, despite professing to surrender, when the boy stepped closer to Carl, Hershel (who was unarmed), and infant Judith. Carl tells Rick he did not want to take his chances by letting someone else live who could potentially kill someone in their group; he brings up how he did not kill the walker on the farm that killed Dale and how Rick's decision to not kill Andrew andThe Governor resulted in the deaths of Lori and Merle, respectively. Carl also appears angered by Rick's decision to take in Woodbury's remaining survivors, who generally appear to be less able-bodied. In season 4 Carl has turned to farming along with his father, Rick tries to encourage Carl to be a kid, but Carl hardened by what he's seen and done is reluctant to do so. He does go to "Storytime" that is hosted by Carol which turned out to be teaching the kids how to use weapons when needed. He tells his father. After an infection breaks out in the prison Rick lets him carry a gun again. In the mid season finale he tells Daryl he has a clear shot on The Governor, but Daryl tells him to not take the shot as a firefight would break out. During the fight he saves his father before finding his sister's carrier empty and bloody. Devastated Rick and Carl leave the prison as walkers invade with Rick telling Carl, "Don't look back."

After the attack, Rick and Carl found a house in a neighborhood. Carl feels like he doesn't need Rick anymore and starts scolding him about how he wanted to plant vegetables and hide while The Governor knew where they were. He goes on to state that he never forgot how to survive while it happened. He is later seen luring 2 walkers away from the house to kill them somewhere where noise won't attract other walkers. He successfully lures them away but encounters a third walker and nearly gets killed. He goes to a house and discovers another walker in one of the rooms. The walker nearly kills him but Carl gets away losing his shoe in the process. He eats pudding he found in the house while sitting on the roof. He later returns to the house and Rick rises from a couch being used to block the door from walkers. Thinking that Rick is dead, he raises his gun at Rick, only to cry saying that he is scared. The next day, as they are sitting near the couch, they hear a knock on the door. It is revealed to be Michonne after she found the pudding that Carl ate the day before. Rick looks at the door and says it's for Carl.

While Rick stays back at the house to recover, Carl and Michonne set out on a supply run where they further their bond, and Carl learns that Michonne once mothered a son. They return from their supply run to find Rick fleeing the house due to it becoming occupied by a hostile group of men. Carl accompanies Rick and Michonne on foot until they come by a train car with a sign attached which points out a sanctuary known as Terminus. Rick decides to travel towards it. On the way there, they are confronted by the hostile group who now have Daryl in their employ. Daryl retaliates against the hostile group, and the confrontation quickly escalates. During the ensuing fight, a man attempts to rape Carl, but is stopped and killed by Rick.

Carl, Rick, Daryl and Michonne continue to follow the tracks, eventually reaching Terminus. Rick decides to have his group sneak into the compound to avoid detection, remaining cautious of its current residents. They find the Terminus members in a broadcasting room, and are greeted by Gareth, the apparent leader. Gareth escorts Rick's group to the courtyard where other Terminus members are situated. Rick notices a Terminus resident in possession of Glenn's watch and quickly deduces that something is wrong. He draws his weapon and demands to know where Glenn and the other people from the prison are. Gareth has his men open fire on Rick's group and strategically rounds them up to a train car. Rick, Carl, Michonne and Daryl are forced to drop their weapons and step into the train car where they are held prisoner. Inside, they are reunited with prison group survivors - Glenn, Maggie and Sasha, along with new group members - Tara, Abraham, Eugene and Rosita.