The Dormouse in Tim Burton's filmed version of Alice in Wonderland is portrayed as a white female mouse named "Mallymkun", or "Mally" for short. She is a swordfighter in training and she also has a secret love for the Mad Hatter (which may be the reason why she gives Alice such a sassy attitude). In fact, the Hatter gave her the weapon she uses, a pin.
As Alice arrives in Underland, Mallymkun, alongside the White Rabbit, the Dodo, and Tweedledee and Tweedledum face upon Alice, thinking she is an imposter, causing Uilleam to take Alice to Absolem, the caterpillar to consult with him so he can verify if she is the real Alice or not. As Absolem tells Alice and her friends to unroll the Oraculum, Mallymkun gazes upon the compendium of event in Underland. After looking at the Oraculum, the conversation between Alice and her friends is interrupted when the Bandersnatch, alongside the Armored Cards arrives and prepares an ambush. During the ambush, Mally strikes the Bandersnatch using her weapon, taking one of the Bandersnatch's eyes with her. Alice, however, manages to escape from the Bandersnatch and the Armored Cards alongside the Knave of Hearts.
Mally, with the Bandsrsnatch's eye tied to her waistband, later attends the Mad Hatter's tea party, telling the Hatter that he brought the wrong Alice just as the March Hare reacts in shock. During a conversation with the Hatter, it becomes interrupted when the Knave arrives, just as the Dormouse drinks the tea nervously. When Mally asks the Knave to come for tea, the March Hare asks him that he is late for tea just as he throws his teacup at one of the Armored Cards instead of the Knave, causing the Hare and the Dormouse to giggle in mischief. She and the Hare later sings "Twinkle Twinkle Little Bat" as the Knave tries to ask the Hatter to find Alice to which the Hatter tells the two to continue singing to which the song is interrupted when Bayard sniffs the Hatter's teapot. The Knave then leaves afterwards as the Hatter is tasked to take Alice to the White Queen for help, explaining to Mally that he should only take Alice to travel, despite loving to travel in hats.
Later while at the Red Queen's castle in a plan to get the Vorpal Sword required to slay the Jabberwocky, Alice meets Mally in the corridor asking her a plan to save the Hatter to which she refuses just as the White Rabbit leads Alice to the Bandersnatch's stable. As Alice notice that the Bandersnatch is missing one of her eyes, Alice asks Mally to get the Bandersnatch's eye and return it to the Bandersnatch. Alice returns the Bandersnatch's missing eye back to its owner, making friends with the beast, allowing her to get the Vorpal Sword. Later, when Mally plans to rescue the Hatter, she tells Alice to escape as her plan to free the Hatter was unsuccessful. Later as the Hatter escapes from executioner with help from Chessur and all the slaves of the Red Queen to fight against their tyrannical leader, she sends the Jub Jub Bird to fight back to which Mallymkun notices what the Red Queen is doing just as the Hatter escapes with her just as the Red Queen summons the Jabberwocky as well for Frabjous Day.
Furthermore, Mally and the rest of Alice's friends arrive at the White Queen's castle and gaze upon the Oraculum showing Frabjous Day where Alice is to slay the Jabberwocky. Later in the Frabjous Day battle, Mallymkun, riding on Bayard, throws her pin into the eye of the the Jub Jub Bird, followed by the Bandersnatch knocking down a group of Armored Cards like a domino effect, causing one of them to drop a rock on a catapult which launches on the Jub Jub Bird, killing him. After Alice slays the Jabberwocky and the Red Queen and the Knave of Hearts are arrested for their betrayal, Mally and the rest of Alice's friends watch Alice return back to the real world.
Mally returns in this film where Alice returns back to Underland has a conversation with the White Queen in Underland where it is explained that Tarrant Hightopp, the Mad Hatter, is in risk of dying. When Alice returns and reports the sad news about the Hatter, Mally and the rest of Alice's friends react in worry and fear that they would lose their best friend if he dies. Alice is then tasked to travel back in time to find the Hatter's missing family and save his life before he dies to which Alice and her friends travel to Time's Castle to help save the Hatter who is in the risk of dying by using a Chronosphere to travel to the past Horunvendush Day event and save the Hatter's family from death before it is too late, just as Alice's friends wish her good luck in helping save the Hatter.
As the lapse in Underland becomes disastrous due to Alice taking the Chronosphere, Thackery and the rest of Alice's friends react in shock due to Alice taking the Chronosphere from the Grand Clock of All Time as the White Queen hopes Alice returns in time.
A past version of Mallymkun appears amongst the crowd during the Toomalie Day event where she and the rest of the crowd felt worried about the failed coronation of Iracebeth. Another past version of Mally appears when Time lands in a past event where she gets into a conversation with Time with the past versions of Thackery and Tarrant to which Time loses his chance to stop Alice while being distracted by them.
As Time returns to stop Alice, the past versions of Mally, Thackery, and Tarrant are unable to leave their seats just as the March Hare feels worried that it is tea time forever.
In the present, Mally and the rest of Alice's friends are gathered near Tarrant lying in his bed gazing at the Hatter who is in the risk of dying just as she and the rest of Alice's friends mournfully leave as the Hatter's hair becomes completely white. Alice manages to save the Hatter from dying when she talks about his missing family still alive just as the Hatter happily wakes up.
After the Hatter is brought back to life and Alice makes a plan to find his missing family, Mally and the rest of Alice's friends arrive at the Red Queen's castle to find the Hatter's family to make him feel happy. Upon arriving, they end up getting jailed by the Red Queen in a jail made of vegetables, much to the Red Queen's notorious plans. Ultimately, a vegetable woman frees them from the jail cell, freeing Alice and her friends in a plan to return to take Time back to his castle and retrieve the Chronosphere to save Underland before it perishes. Mally and the rest of Alice's friends end up getting engulfed by time rust along with everyone in Underland. With the Chronosphere back in place, Mally is brought back to life along with everyone caught in time rust. Alice then leaves Underland just as Mally watches Alice returning to the real world alongside the rest of Alice's friends.