Mr. Potato Head (often referred to as simply Potato Head) is a moody Mr. Potato Head doll by Playskool. He is outspoken, sarcastic, wisecracking, sometimes dumb, hot-headed and jealous. A potato-shaped toy, his patented design allows him to separate his detachable parts from his body by removing them from the holes on his body. He also has a compartment on his lower back to store extra appendages. For unknown reasons, he is the only toy shown to be capable of retaining control over his parts even if they are several centimeters/inches away from his main body. For example, he can still see if his detachable eyes are removed, as well as being able to move his hands if they are detached. The same thing applies to his "Mrs." counterpart.

In Toy Story, when he becomes fascinated with all the features of the Buzz Lightyear action figure that Andy has received for his birthday, Potato Head also makes fun of Woody for not having a laser like Buzz and by describing Woody's sampled voice "like a car ran over it." After Buzz is knocked out of the window, Potato Head is quick to accuse Woody of being a jealous "toy-killer," thinking that Woody might do the same to him if Andy plays with him more often, and leads a mutiny with the other toys. As Andy is looking for Buzz, Potato Head whistles at Woody, holding Etch and it means that Potato Head will choke him and kill him. He is somewhat happy when he learns about Woody's disappearance, as he admits Woody's guilt in the window incident. Later, Woody throws a string of Christmas lights from Sid's house to Andy's house; Slinky catches it, but Potato Head snatches it away and calls Woody a liar. Woody then tries to convince the toys to let him get back by pretending that Buzz is with him, but Mr. Potato Head remains suspicious of what Woody is actually doing. When Woody blows away the cover by exposing Buzz's severed arm, Potato Head furiously labels him a "murdering dog" as the toys back away from the window, leaving Woody depressed and stranded in Sid's house. During the move to Andy's new house, after Woody tosses RC onto the street to rescue Buzz, Potato Head orders the other toys to "toss him overboard;" however, when Bo Peep reveals that "Woody was telling the truth," all of the toys are guilty for their misunderstanding, especially Potato Head for having Woody thrown off. He holds Slinky's tail to help Woody back at the truck. He was hit by Slinky after he loses his grip on Woody. When Woody tosses RC in the truck, all of the toys dodge, but Potato Head was hit and crushed by RC. At the end of the film, he is surprised to hear Molly receiving Mrs. Potato Head for her Christmas present.

In Toy Story 2, after Al McWhiggin of Al's Toy Barn steals Woody, he is shown in a much more positive light by going on a mission with Buzz, Hamm, Rex, and Slinky to rescue Woody. When he finds out that Al is the man who stole Woody and also is the guy who wears the chicken suit, he is shocked. Later, when they are going to leave, Mrs. Potato Head packs some extra pair of shoes and angry eyes on his back compartment. At one point, when the toys are reprimanded by Buzz for requesting a rest, Buzz mentions the time when Potato Head has ordered Woody to be thrown out of the moving van in the first film, and Potato Head is shown to still be regretting this greatly, even though amends have already been made. When the toys cross the street to Al's Toy Barn, they cause a semi to jackknife, and the chains restraining a large pipe on the semi break, freeing the pipe, which rolls down the street, during which Mr. Potato Head gets one of his feet stuck in a chewing gum and has to pull his foot off the gum before the pipe can crush him. When the toys search Al's Toy Barn, Potato Head takes the wheel of the car that Hamm has been driving, but when Tour Guide Barbie hops into the car, Potato Head remarks "I'm a married spud," making him and Hamm exchange seats. After the toys break into Al's room, Potato Head attempts to frighten Jessie by reaching into his back compartment for his angry eyes, but attaches his spare pair of shoes by mistake. When the toys leave the apartment after Al leaves with Woody, Potato Head throws his hat like a frisbee to jam the closing doors, letting the toys pass through. Outside, he is the first to spot an idling Pizza Planet delivery truck nearby. While the toys chase Al in the truck, Potato Head saves three alien toys from flying out the window. In the airport, when he sees the luggage area, he gasps and his angry eyes and pair of shoes come out after his compartment opens. He initially feels annoyed when the aliens repeatedly express their eternal gratefulness towards him, but after the toys return home, he reluctantly gives in to his wife's decision to adopt the aliens as their children. In the outtakes, Mrs. Potato Head is shown packing a lot of things behind Mr. Potato Head's compartment. In the last outtake, Mrs. Potato Head puts monkey chow and says "Come here, monkeys." and they are harassing Mr. Potato Head, Mr. Potato Head tells the crew to call his agent.

In Toy Story 3, he is seen to be still resentful of the aliens as his children, who still worship him for saving their lives. Again, Potato Head is the most doubtful toy of Woody when he and the other toys are almost thrown away. When Lotso's true colors are revealed, he is the most vocal critic, and tries to defend his friends and wife from Lotso. However, Lotso has him thrown into a sandbox overnight to "learn some manners." When Woody returns to Sunnyside with an escape plan, he acts as a signal to the other toys and purposely gets himself back in the box. His body parts separate from his body, and use a tortilla as a body. However, the tortilla is eaten by a bird, so Potato Head uses a cucumber instead. He remarked he felt terrible feeling so fresh and healthy in his vegetable body. The aliens return to him his body, but the toys end up in a landfill, facing death at the hands of an incinerator. Potato Head and the toys are saved by his children, who he finally accepts as his true children, and declares himself to be eternally grateful, just as the aliens had told him when they met. When the toys are donated to Bonnie, he is seen being pestered by the Peas in a Pod.