Mandy is the main antagonist for the girls at high school (and university) when they are not on spy missions.
Mandy's rivalry with Clover is the most pronounced. They often compete over boys, popularity contests, bragging rights, the latest fashions, and virtually everything else. Mandy will go out of her way to annoy the girls and get them in trouble, and will even use dishonest means in order to do it.
In Season 1 - Season 4, Mandy is often accompanied by her two BFFs/yes-women Caitlin (Alex's rival) and Dominique (Sam's rival). However, it wasn't until Season 4 that there was actually any loyalty between the three. Before then, they had each been shown to leave the others at the drop of a dime. At the start of Season 5, Mandy and her crew apparently went their separate ways after graduating from Beverly Hills High. While Mandy was supposed to attend a ski school in Aspen, she transferred to Malibu to attend Malibu University with her cousin Mindy. Mandy and Mindy, known by the girls as the Terror Twins (though they are only called that in "Evil Sorority"), are seen together for most of the fifth season, save for the finale.
In the episode "Evil Coffee Shop Much?", she follows the girls to WOOHP and her attitude impresses Jerry, who makes her a WOOHP spy. However, she dislikes the experience and eventually asks to have her memories erased at the end of the mission.
In "Totally Busted", Mandy is infected by SUDS, along with Caitlin and Dominique, and they are transformed so they hunt spies, that is, they are "spy-ssassins". They try to kill the spies but are all easily defeated. Later, Mandy, Caitlin, and Dominique kidnap the spies' mothers and take them to Mandy's ski chalet at the Sugarflake Ski Resort. They put the moms in a tram cart that is let loose. After an avalanche incident, Mandy and her cronies kidnap the spies to The Groove (Beverly Hills' main shopping center where Mandy says she does her deepest thinking). After they learn about the SUDS, they infect the spies with it and rescue the Inventor from Prison. Later, Mandy, her cronies, and the Inventor plan to transform the whole world into an army of spy-ssassins, but were all defeated by the spies. At the end, Mandy, Caitlin, and Dominique are returned to normal.
In "Totally Dunzo", Mandy becomes nicer to Sam, Clover, and Alex after suffering from a "near-death experience" (breaking a nail). She returns Sam's, Clover's, and Alex's parking space that she had just forbidden, pays for the shoes Sam, Clover, and Alex were just about to buy and cleans their entire penthouse dorm room when they were not looking. At the end of the episode, when she discovers that the girls were spies, she goes back to her usual snobbish self because she believes "friends shouldn't keep secrets from each other" and demands to go back to Malibu University. As the episode was intended to be the series finale, Mandy's memory is not erased, but when the series was given a sixth season, she gets her usual memory wipes. She is also frequently saved by the spies from the villains who have a vendetta against her.
In "Baddies on a Blimp" Mandy is mentioned by Blaine after he tells Clover that he had enough of dating L.A. girls and she was the last L.A. girl to be dated by him. This prompts Clover to take a break of dating her ex-boyfriends in the last part of the episode.
Beverly Hills High
It is implied that she does poorly in school as seen in "Dental? More Like Mental" and made clear in "Alex Gets Schooled" when it turns out that there was a mix-up at Beverly Hills High, and that the report card containing all F's belonged to her and not Alex, who got As and Bs. She was also punished in "Silicon Valley Girls" (she was booted out of the student court for failing to enforce the school's dress code when she was appointed student court judge, after Clover was too lenient and showed favoritism towards Sam and Alex). In "Morphing Is Sooo 1987", it is revealed by Alex that Mandy had braces that were taken off in 7th grade. In "Evil Graduation", although she entertains the idea of staying in high school forever like Chet, she graduates along with the other girls.
Mandy originally planned to go to a ski school in Aspen but ends up going to Malibu University where she lives in the same dorm as the girls and shares a room with her cousin Mindy. She has pledged the same sorority as Clover during Greek week in "Evil Sorority". She tries to get the girls in trouble by taking incriminating photos of them trashing the dorm along with her cousin in "Virtual Stranger" although she and Mindy later is caught in related photos. When her room floods in "Miss Spirit Fingers (Jazz Hands Return - Part 2)", she and Mindy move in and redecorate the girls' room but thanks to Jerry, they're flooded out of the girls' penthouse.
Being a model of the "popular teenager" stereotype (in her own opinion), she is shown to be stylish, charismatic, popular and pretty but is also bratty, materialistic, snobbish, egocentric, greedy, arrogant, cruel, naughty, abusive, and downright maleficent. She apparently may have inherited these negative traits from her mother, Phoebe. Her father is never seen, but he's mentioned in the series (and it is also implied that her parents are in fact married). She has a high, squeaky voice with a nasal laugh. However, Mandy does actually have a nicer side to her personality, but whenever she becomes nice to people, it never lasts long and she goes back to being mean and selfish if she is provoked in one way or another.
Mandy shows her belief that she is the best at "everything" shown in the "Black Widows" prior the Spelling Bee and in "Sis-KaBOOM-Bah!". The reason for this is most likely her need for attention and wanting to feel important.
She has long black hair, violet eyes, a beauty mark under her left eye, and fair skin. Her primary outfit is a red dress under a white long sleeve button shirt and white boots. Her primary outfit is been slightly altered like Clover's primary outfit. Mandy sometimes has her hair tied in a high ponytail with a light blue scrunchie.
Her formal dress; as seen in "Matchmaker", "Attack of the 50 Foot Mandy", "Danger TV", and "So Totally Versailles!"; is a long sleeveless purple dress. Mandy wears a lot of purple on the show, which is presumably her favorite color.
In "Evil Professor" She wears a dark magenta denim jacket under a light pink tank top, red skirt and black boots. This outfit however has minor changes in Season 6; in "Clowning Around!" her red skirt changes to pink, while in "Astro-Not", her jacket is replaced with a different shaded purple jersey jacket and her tank top is white.
In Season 6's two part finale of “So Totally Versailles!” Mandy wears a light purple/violet and white long-sleeved dress as her hair is transformed into a classic styled look and her black wig is extended into Marie Antoinette styled ringlets.
One of Mandy's BFFs/yes-women. She has a snobby attitude and is almost always there for Mandy, but until Season 4, there was very little actually loyalty between the 3 girls. She appears to be one of Mandy's closest/only friends, because whenever Mandy is not with Caitlin or Dominique, she does not seem to hang out with anyone else. However, Mandy never mentions her while she is at Malibu University as Caitlin and Dominique did not go to the same university. This implies that they were simply "high school friends" and not genuine friends. At the end of "Child's Play", Mandy was shown to be going out with her older brother, Rick, who was mentioned to be a senior at Beverly Hills High in that episode.
One of Mandy's BFFs/yes-women. She has a snobby attitude and is almost always there for Mandy, but until Season 4, there was very little actually loyalty between the 3 girls. She appears to be one of Mandy's closest/only friends, because whenever Mandy is not with Caitlin or Dominique, she does not seem to hang out with anyone else. However, Mandy never mentions her while she is at Malibu University as Caitlin and Dominique did not go to the same university. This implies that they were simply "high school friends" and not genuine friends.
Mandy's cousin who replaces Dominique and Caitlin in "Evil Professor" and onwards. Mindy is essentially just a blonde clone of Mandy, although she has a tanner skin tone, a calmer demeanor. Mindy also speaks using the Southern American English dialect, showing that she is from the Southern United States.
Clover is Mandy's primary enemy. The two girls have apparently hated each other ever since they met, according to a comment Sam made in "Attack of the 50 Foot Mandy". In "Totally Spies! The Movie" Mandy instantly went on the offensive and attacked Clover, Sam, and Alex. However, in the series Clover is the target of Mandy's worst actions. In "Malled" Mandy attempted to frame Clover for shoplifting even though Sam was the person who made the verbal counterattack.
Mandy's not as a big of a rival to Sam as she is to Clover, but she has competed with Sam over some things in a few episodes. Some examples include the Beverly High annual spelling bee, and when Mandy discouraged Sam from competing in the Youth Spirit contest. Mandy once attempted to be friends with Sam after the latter saved the former's hair from a pottery incident.
Mandy and Alex are also rivals, though not to a great extent. Mandy's comments tend to be centered around Alex's social standing. In comparison, Clover is always attacked as an individual.
In "The Anti-Social Network", it is shown that Mandy did not accept Telly Hardwire's online friend request in high school. As revenge, he creates 'Mandybook', a social network with the ability to control minds. He builds up Mandy's popularity at Malibu University dramatically before turning her followers against her.
In "Grabbing the Bully by the Horns", it is revealed that Mandy was one of Timmy's childhood bullies. The hologram displayed by Timmy's robot suit shows that she put cotton candy on his head after he had already been taunted by two other bullies. Mandy and the other two get put through his 'bully gauntlet' as an act of vengeance for bullying him.
In Season 6, Mandy gets an intern named Trent. Trent has a mild and meek personality and is frequently mistreated by his boss. In the episode "Trent Goes Wild", it is revealed that, like Arnold Jackson, Trent has a subconscious desire for revenge against her. This desire is expressed when he is turned into a half-human-half-scorpion hybrid creature due to a mix-up of DNA at the WOOHP lab.
- Mandy's grade history.
- Mandy's memory is partially erased in:
- In "Stuck in the Middle Ages with You" she wins first place in the Beverly Hills High Halloween party costume contest as a witch.
- In "I Want My Mummy" she is disqualified from the Beverly Hills High Most Charitable Teen contest after it turned out that her ruby ring was actually a fake ruby.
- Mandy is the only character to have her height revealed on the show. In "Attack of the 50 Foot Mandy" Clover says that Mandy is 5' 8" in 4-inch heels, making her actual height 5' 4".
- Mandy has never been a love interest/lust object for a major villain despite her self-proclaimed attractiveness, except in "Ski Trip" when she is accidentally captured by Gelee, who mistakes her for Clover due to Mandy's red ski suit (which Clover said was identical to her catsuit), and in the episode "Halloween" when she was also made the Evil Ghost's queen after she inadvertently caused a zombie plague on Halloween night in the Vista Verde Estates gated community. She is also made Auguste's queen after he notices her, after revealing he plans to rule France and the whole world.
- In "Trent Goes Wild" we learn Mandy is allergic to shellfish.
- In "Halloween" she freed an evil ghost who made her his queen as the reward. Whether this means she is actually a witch or anyone could release him with the spell is not known.
- In "Halloween", when she faints, she stays asleep for most of the episode.
- In "Ski Trip", she is forced to learn how to play chess because of Gelee, during which, she remarks that Gelee isn't even that good at the game.
- In the b-story of "Black Widows", it's shown that Mandy has stage fright when she walks into the Beverly Hills High auditorium and sees how many people are there for the annual spelling bee. It also reveals Mandy relies on her family's money in order to gain what she wants.
- Mandy has a fan club at school called MIG (Mandy Is Great), in which she is the QB (Queen Bee). When Clover joins, not knowing it was Mandy's fan club, she makes Clover massage her feet. ("W.O.W.")
- Queen Bee is the name of how Mandy became, in a reference for when Chloe Bourgeois had a nickname in Miraculous: Tales of Ladybug and Cat Noir.
- In "The Dream Teens", it is revealed she was on the yearbook committee, but did not have the final say on how the picture was laid out for Most Photogenic. She has also worked on a student paper like her mother had when she went to Beverly High. When she formed her own spy club, she took embarrassing photos of Clover and Alex.
- In "Totally Busted", she has a ski chalet whose front is shaped like the letter M.
- In "Sis-KaBOOM-Bah!" it is revealed that Mandy has nail polish, hair gloss, and fake eye lashes in her locker. Clover notes she does not have nail polish remover.
- Dominique and Caitlin seem to be her closest, or either, her only friends, because whenever Mandy's not with either one or both of them, she doesn't seem to hang out with anyone else. In fact, Dominique and Caitlin seem closer to each other than they do to Mandy.
- She is very bad at sports.
- Outside of WOOHP, not including the villains, and of all the Beverly Hills students, Mandy witnesses the spies the most as being ones whenever they are in a mission, even if her memories of them get wiped out frequently after that. This is especially best exhibited in the episode "Evil Coffee Shop Much?", where she was unwantedly recruited with them for the mission, and later voluntarily asked for her memory to be wiped out after that experience.
- In the English version, she is voiced by Jennifer Hale, who also voices Samantha.