Madame Gasket is first seen running the Chop Shop: a massive factory where discarded metal and outmoded robots are collected, recycled, and recirculated. In order to increase her profits, she had her son Ratchet take control of Bigweld Industries, the world's sole provider of spare robot parts (for some odd reason) and have it instead distribute upgrades (which for another odd reason, seems to be more advantageous and profitable).
Through this, she intended to render the city's lower class population outmoded and presumably resell the resulting scrap metal to upgrade manufacturers. As a mother, she is very fond to Ratchet. Otherwise, she can be somewhat mean-spirited and villainous to him. In the film's climax, in an epic battle with Bigweld, Rodney, and the others; she was about to order her robotic blacksmiths of Chop Shop workers and giant sweepers to attack the protagonists when Piper came to the rescue with all the outmodes Rodney had repaired prior. During the battle as Gasket's army is being defeated, she tries to finish Bigweld off, but he is rescued by Rodney. Gasket then battles Wonderbot, but is overpowered and thrown into a slag pot and into the melting furnace.
When the pot swings out of the furnace, Madame Gasket was burned and exploded in the furnace, much to Ratchet's horror. Ratchet then loses all of his upgrades and ends up chained next to his father.
Madame Gasket is the power-hungry and diabolical mastermind behind the plan to kill off "outmodes". She is shown to be a truly greedy, ruthless, hot-tempered, vituperative, psychotic and manipulative individual. She has her son named Ratchet, to execute her plan by tempting him with the thought of more money and less rusty robots. It is unknown what she has against outmodes as she could easily be considered one herself due to her appearance. Madame Gasket is also the head of an underground factory called the Chop Shop, which melts down discarded scrap metal (and in some cases, outmodes who are still alive) to turn into upgrades. She has no problem with killing off other robots, as she tried to have Bigweld dumped into the Chop Shop's furnace, and she ordered her army of mutant robots to turn Rodney and the other outmodes into scrap metal.
Although she is extremely sinister, loathsome, malevolent, destructive and unscrupulous, Madame Gasket does have a soft, honest, motherly, optimistic, affectionate and delighted side, which can be seen whenever Ratchet is around (which is also her only redeeming quality). She genuinely cares for him as she gave him a framed picture of herself captioned "World's Best Mom" and praised him when he agreed to help carry out her plan. Ratchet later presented her with an army of shiny, upgraded sweepers to use for killing outmodes, much to her compassionate and enthusiastic delight.
Madame Gasket is a fearsome-looking robot with glowing yellow eyes and a metal unibrow. She has a claw for her right hand, and a sharp, pincer-like weapon for her left. She travels on three large wheels that are hidden under the rest of her body. The top of her head appears to be some kind of motor with saw blades in it, which is always spewing out smoke. Because of her unnatural appearance, many other robots (namely Fender) mistake Madame Gasket for a man. Ratchet is embarrassed of her looks. She has a set of wires with a harness (resembling suspenders) which she uses to get around the Chop Shop.
All right, break time. (robots look up at her) All right, break time's over.
~ Madame Gasket's first words.
(Ratchet: Oh, yeah. I have never felt so relaxed. Say, do you mind giving me a little scratch between the shoulder blades? Ah, there you g... Aah! Easy, tiger. Oh! Hey, take it easy! Hey, what are trying to do, kill... AHHH!!) Relax, it's me, your mommy. (Ratchet: How did you get in here?!) I came up the air shaft. I know you don't like anybody here to see me. (Ratchet: Well, what do you want?) Someone's fixing them! (Ratchet: What?) Someone is repairing outmodes! And they are laughing at you! (Ratchet: Who? And are you sure they're not laughing with me?) Yes. (Ratchet: Oh! So what if one crazy fanatic repairs a few outmodes? Who cares?) Think. Use those brains I stole for you. Today, it's one. What about tomorrow when everyone gets the idea this is okay? "We can fix ourselves. We don't need upgrades. We want Bigweld." Then what happens to you?! (Ratchet: Okay, okay. Take it easy. We've got to find out who this is and stop him.) Not stop him, crush him! Destroy him! And by the way, I brought you a little something for your desk.
~ Ratchet and Madame Gasket about their plot.
(Bigweld: Gasket, you're a sick, twisted, evil robot.) I try.
~ Madame Gasket about to kill Bigweld.
Oh, good, company! So, you're the little glob of tin who's been making all the trouble.
~ Madame Gasket meeting Rodney and his friends for the first time.
Who are these losers?! (Fender: We sir...) I'm a woman.
~ Madame Gasket correcting Fender that she's a woman.
While you're at it, count these.
~ Madame Gasket revealing her upgraded fleet of super-sweepers.
What are you doing?! Get off me! Let me go, do as I say, get OFF!
~ Madame Gasket's last words to Ratchet before she explodes.
It is unknown why or how she became evil or why she is against outmodes, especially since she herself is an outmode. It is possible that she was separated from the rest of the outmodes, eventually becoming a "sick, twisted evil robot".
Despite being a female, she was voiced by the male actor Jim Broadbent.
It was thought that Ratchet drove the plot of the film, but Gasket is the one who drove it, as she is behind Ratchet's plot to take over Robot City in the first place.
Gasket is the first antagonist of a Blue Sky Studios film who is a parent.
Gasket is also the first female antagonist in a Blue Sky Studios film.
Whoopi Goldberg was considered for the role of Gasket, but it was ultimately decided that Gasket would be voiced by a man.