Abby Mallard is the tritagonist of Chicken Little. She is a female duck (implied swan) with buck teeth and wearing a purple shirt and some hairbands. A slight speech impediment and a long, asymmetrical face earned her an unfortunate nickname from the less polite children. She is accustomed to being teased for her awkward appearance and takes a generally optimistic approach to life. She is one of Little's best friends and harbors a secret crush on him. She is voiced by Joan Cusack who also voiced Jessie.
Abby is first seen in class, making her teacher jump by her voice and appearance right after Foxy Loxy fakely cough out the words "ugly duckling." Later, she was at the gym talking to Chicken Little while playing dodgeball. Chicken Little said that he had a plan, Abby thinks that closure, where one has a conversation about feelings, would be more helpful especially when it comes to Chicken Little's dad. But despite trying to convince him with magazines and trying to get Runt and Fish to agree, Chicken Little decides to stick to his plan.
When Chicken Little joins the baseball team, Abby, along with Runt and Fish, helps him train for the games. On the day the Acorns team goes against the Peanuts, Abby was seemly in charge of putting up scores and cheers along with everyone else for Chicken Little's success. Abby, Runt, and Fish, were celebrating at her house when Chicken Little called her about the "piece of the sky." Abby, when she learned that Chicken Little didn't tell his dad about it, tells him again to use closure to deal with the problem. When Fish was taken the object, Abby and the others follow Fish's glowstick to the baseball field where they saw that the object was just a part of an alien spaceship.
They went inside the ship to get Fish and, while there, saw a map of the solar system where most of the planets were crossed out and Earth was circled. Believing that the aliens were planning an invasion, the gang ran out of the ship and ended up being chased the aliens themselves. Abby suggested to rang the school bell to alert Oakey Oaks about the aliens, but while Chicken Little was ringing the bell, the aliens dislike the bell's ring and fly off into space before the citizens can see them. The citizens believed that Chicken Little has gone crazy again and Chicken Little's father was embarrassed.
The next day, Abby tells Chicken Little to try to talk to his dad, but Chicken Little thinks it's too late. While Abby was walking away with Runt and Fish, they hear Chicken Little's scream and came to see what's going on only to find a little alien with him. While learning that the alien's name is Kirby and that he was left behind from his parents, the sky appeared to be cracking and it's revealed to be alien spaceships attacking the town. Chicken Little ran after Kirby while he was running around dangerous streets. Abby soon found Chicken Little and his dad arguing and tell them that they should stop messing around and deal with the problem. Even though Abby meant the invasion, Chicken Little and his dad had a closure conversation which did help them understand each other and Buck decides to help his son. Chicken Little and Buck sets off to help Kirby, but Chicken Little quickly ran back to Abby and kiss her before proceeding the mission. Abby was enchanted by the kiss, even while helping Runt with the firetruck to get Chicken Little and his dad into the City Hall.
The misunderstanding was eventually solved between the alien and the citizens of Oakey Oaks. A year later, a star trek version of Chicken Little's adventure was in the theater. Abby and Chicken Little were there watching the movie and enjoying the popcorn. When their hands touched, they pulled themselves back, look away and blush; but then they close in on each other and hold each other's hands.