Mimi is a villain and a minion of Count Bleck in Super Paper Mario. She has a violent and cruel temper and uses her appearance as a cute and innocent girl to lure travelers into becoming slaves. She possesses the ability to shape-shift, often taking the disguises of Merlee and other characters, hence her name, that is derived from the word "mimic". According to the InterNed, Mimi's theme is called "Mimi the Copycat" and her battle theme "I'm Not Nice". Her true form is that of an evil-looking robotic spider, seen during most of the battles against her. Whenever Mimi is in her true form, her dialogue box is in a shade of purple with white text color, similar to the Shadow Queen and Bonetail in Paper Mario: The Thousand-Year Door.
 Super Paper Mario
Mimi first appears in the game Super Paper Mario during the meeting of Count Bleck's minions which occurs after Mario enters the door to Chapter 1. However, Mimi's name and her actual form is not seen in this cutscene, as she uses her transformative abilities to appear like various different characters. She first takes upon O'Chunks's form and due to this being the introduction to the villains, seems like she really is the bulky minion, until the real O'Chunks pops in. Then, she takes upon Count Bleck's form to scold O'Chunks, Princess Peach's form to accept the Count's compliment on her shape-shifting, then Bowser's form to yell at Dimentio for reading her diary (a reference to the first Paper Mario).
Mario and Peach first encounter Mimi in her normal form when they reach Merlee's Mansion in Chapter 2-2. Unbeknown to the heroes, Mimi had been sent there by Count Bleck to defeat them before they can obtain the next Pure Heart, which Merlee has taken with her into hiding. Taking the disguise of Merlee's handmaid, Mimi makes her first attempt on Mario and Peach's lives when she tells them that Merlee is in the room above them. When the heroes enter the room, the door is covered by bars and the roof begins to lower. Mario escapes the trap by flipping into 3-D, and continues his search for Merlee, He and Peach eventually release Merlee's pet, Gnaw, which chases Mimi away.
In Chapter 2-3, Mimi orders Mario and Peach to work off a debt of one million Rubees after they break a vase. Using their new Pixl friend, Slim, they discover a secret stash of Rubees, allowing them to pay off the debt. This causes Mimi to go into a shock, saying it was "impossible" to earn one million Rubees and claiming the "wonderful curse" she put on the mansion was broken. She then flees by appearing to explode.
In the last part of Chapter 2, Mimi impersonates Merlee and asks Mario to sign a contract to pay off 10 million Rubees for the Pure Heart. However, a ghost-form of the real Merlee warns the heroes that it was a fake. Mimi gets angry and morphs into her Rubee-shooting "true" spider form, which is impervious to attacks at this point (Which is similar to Tubba Blubba being impervious for not having his heart with him). She chases Mario, Peach and the Pixls around the mansion's basement, spawning at their location whenever they take too long to move on from a room. After a long and grueling chase, Mario and Peach find a bathroom at the bottom of the basement where Merlee is hiding with the Pure Heart. Mimi then appears and in a flash of light she transforms into Merlee. To decide which Merlee is the real one, a contest is held where Mario must ask each of the Merlees five questions to decide which one is the real Merlee. Regardless of whether or not the heroes choose correctly, Mimi attacks Mario and Peach, but Merlee removes her invincibility with cheer-leader-like chants. It is noted that Spider Mimi's legs fall off after taking enough hits. She is then defeated by Mario and flees the mansion.
Mimi is fought again in Chapter 6. Posing as King Sammer, she tells Mario that the Pure Heart is in the chest beside them. When opening the Treasure Chest, Mario finds a bomb, and, when he isn't fazed by the explosion that erupts from it, Mimi attacks him, this time in her girl form, to waste the rapidly declining time before Sammer's Kingdom is destroyed by The Void. Although she loses in the battle, she succeeds in her goal as Sammer's Kingdom is destroyed.
In Chapter 8, Mimi poses as Merlon and tells the heroes to hit a "totally unsuspicious" ! Block. When struck, it causes Mario and Co. to fall into a pit. She then disguises herself as Merlee once again, and asks three questions on what Mario is afraid of; she places the items or enemies in a corridor up ahead, and when the heroes survive, she gets upset and insults Peach. While Mario and Luigi continue on through the castle, Peach and Mimi have a one-on-one battle, ending in Mimi's defeat just as the room begins to fall apart. Mimi almost falls into a hole in the ground, and even though Peach grabs her by the leg in an attempt to save her, the girl is too heavy for the princess and they both fall into the trench.
Mimi is revealed to survive when she and O'Chunks come to Count Bleck's aid after her fellow henchman, Dimentio, takes over. She warps herself and O'Chunks to Dimension D to help the Count. Mimi and O'Chunks' love for Count Bleck helped Mario, Peach, and Bowser defeat Super Dimentio. This action redeems Mimi.
After the game is beaten, she gets a job working as Merlee's actual maid, and, since Merlee rarely uses her mansion (as she had moved to Flopside far earlier in the game), she decided to turn Merlee's mansion into a stable of cutie-pies (otherwise known as boys). One of Mimi's former slaves says Mimi is making him pay for the time he spent in the mansion while she was away, he however is delighted at this because he now has something to do. To help raise money for her stable, she begins the creation of a Cutie-Pie Video Game and a Cutie-Pie Cafe.
 General information
Mimi gives a lot of information about herself in the game show "That's My Merlee!". Whether it is true or not is debatable, as she was disguised as Merlee at the time and may have been attempting at making Mario and friends think that she was the charmer. However, it is very likely to be true as Mimi has stated before that she likes men and also states it in the show. Also, when asked what her favorite animal is, she replies "an adorable little demon", a demon being her favorite animal would match Mimi's personality.
Other aspects of Mimi's personality are revealed throughout the game, such as her fear of the dark. She also enjoys fashion, and is the one of the only characters in Super Paper Mario to change their outfits. Mimi wrote in her diary that her dream of a perfect world is a gem-filled pool with hunky lifeguards (as revealed by Dimentio); this is one of the many times Mimi is shown to have a love for gems (especially Rubees) and boys.
 Powers and abilities
Mimi has a large number of powers. The most notable are Mimi's shape shifting ability and the invicibility that Count Bleck gave her. She has numerous powers that involve her beloved Rubees and can also transform into a spider-like form. First her head turns upwards to the right, then it swings back (whilst emitting a number of loud cracks). After which, it starts spinning almost uncontrollably with her eyes large and round. It stops upside down. In the first fight, her bow loses color and the lines unfold into a pair of her legs. Her eyes and arms stretch out into the other two pairs after a casino-esque jackpot noise.
When in her spider form she can shoot Rubees at the heroes; she can also tuck in her legs and fly around the room with pointed Rubees sticking out of her. When in her girl form, she can form a barrier of Rubees around her. In both forms she can cause a wave of Rubees to come out of the ground, dealing damage to anything it touches. Like Mario and Dimentio, Mimi is gifted with the ability to flip to 3-D. Mimi can also float in the air, fly and warp to different locations.
Mimi's true identity is shrouded in mystery. There are two theories, according to Carson, that may explain who Mimi really is: a failed Pixl created by the Ancients, or the unintended result of a witch's experimentation with shape-shifting potions. A third theory could be her spider form, in which Mimi calls her "true form," although this could just be her main fighting appearance. If Mario flips into 3D, the player can see gears from inside Mimi's spider form, implying that Mimi may be a robot altogether. This could be supported also by the fact that she apparently explodes into pieces in Chapter 2-3, but survives.
 Names in other languages