Lizzie and Mika Samuels

Lizzie and Mika are first seen in the fourth season premiere, "30 Days Without an Accident", with other children who are naming the walkers outside the fence, which leads Carl Grimes to tell Lizzie that they are not people, that they are not pets, and that they eat people, concluding with telling her not to name them. In the episode "Infected", their father is bitten when walkers get loose in the prison, and before dying he asks Carol to look after his daughters. Lizzie expresses intentions to stab his corpse in the head to prevent reanimation but is emotionally unable to. Carol does it instead, and later tells Lizzie she is weak and needs to toughen up. Mika calms down her sister by telling her to "look at the flowers". In the episode "Isolation", Lizzie gets the flu and is forced into quarantine, and Carol is disturbed by Lizzie's apparently personal connection with walkers. In the episode "Indifference", Carol talks to Lizzie before departing with Rick, and Lizzie accidentally calls her "Mom". In the episode "Internment", when some infected residents succumb to the virus and reanimate, Lizzie rescues Glenn from a walker by leading it away. After being treated with medicine, she plays with Glenn's blood. In the mid-season finale episode "Too Far Gone", when the Governor attacks the prison, Lizzie convinces the other children to help in the battle. She and Mika carry Rick's baby daughter Judith and rescue Tyreese from two of the Governor's soldiers – shooting Tara's girlfriend Alisha in the head.

In the episode "Inmates", Lizzie, Mika and Tyreese are shown to have escaped the prison with Judith. Lizzie kills a group of rabbits, and during a walker attack she covers Judith's mouth to try to stop her from crying but nearly smothers the baby. Carol finds the children, and then takes them to Tyreese. In the episode "The Grove", they come to stay at an abandoned farm with a pecan grove. Lizzie shows great distress when walkers are killed and Mika is unwilling to toughen up and become hardened, due to her compassion for others. Lizzie believes that walkers are "just different" and that they want her to "feel the way they feel" rather than kill living humans, but Mika reassures the adults that she is not like her sister, and understands that walkers are dangerous. Carol and Tyreese come back to the farmhouse after gathering food in the woods and they see that Lizzie has stabbed Mika to death and plans to do the same to Judith. Lizzie tells Tyreese and Carol that she has spared Mika's brain so that she will come back as a walker, and asks them – at gunpoint – to leave Mika's body alone. Carol later kills Lizzie after taking her outside to "look at the flowers" to distract and calm her. Tyreese reveals that Lizzie had admitted to being the one at the prison who fed rats to walkers at the fence (as seen in "Infected") and who dissected the rabbit that Tyreese found in the tombs (as seen in "Too Far Gone").

In the episode "Consumed", Lizzie and Mika's corpses appear in a flashback when Carol and Tyreese are burying them.

In the mid-season premiere "What Happened and What's Going On", Lizzie and Mika appear as hallucinations, along with Beth Greene, Bob Stookey and The Governor, in Tyreese's mind as he is dying from a walker bite. They try to comfort him and assure him he made the right choices and that it is OK to move on while Martin and the Governor taunt him about his actions and their consequences. For a moment Lizzie and Mika hold out their hands, which he holds, but in reality this is Rick holding his arm out so Michonne can amputate it. When Tyreese is bleeding out in the car he sees Lizzie, Mika, Beth and Bob once more; he decides that he wants to let go and join them, and dies peacefully.

In the third episode of the season, Ghosts, Carol looks at the cover of a textbook and hallucinates seeing herself at the head of a table with Lizzie, Sophia, Mika, Sam, and Henry with blood over their necks sitting around the table.