|Hair color||Brown (s1-s5, s14-s15)|
|Residence||Crosswires' Mansion, Elwood City|
|Family||Mary Alice Miller (great-great-grandmother)|
Edzel E. Crosswire (great-grandfather)
Taffy Crosswire (great-grandmother)
Olga Crump (great-aunt)
Ed Crosswire (father)
Millicent Crosswire (mother)
Chip Crosswire (brother)
|Book debut||Arthur and the True Francine|
|Cartoon debut||"Arthur's Eyes"|
|Voiced by||Melissa Altro|
Mary Alice "Muffy" Crosswire is a third grader in Mr. Ratburn's class at Lakewood Elementary. She is the richest girl in Elwood City, and lives in an enormous mansion. Muffy entered Lakewood in second grade, when she met Arthur and his friends and quickly became best friends with Francine. She is often labeled as snobbish and spoiled because of her wealth, attitude, and frequent selfishness.
Muffy is a medium-skinned anthropomorphic monkey. In the first season, she was rendered with buck teeth, but they seemed to have disappeared in the later episodes. Her usual outfit is a purple puffy dress with a lavender fabric belt over a long-sleeved white blouse, finished with brown Mary Janes with knee-length white socks. Muffy's hairstyle consists of two long auburn braids tied with a pair of matching purple bows. She is seen with this hairstyle in most of the episodes but sometimes changes the style, especially for formal events.
Her pajamas consist of a purple and white nightgown under a lavender robe and pink slippers.
Her swimsuit consists of a purple maillot with an orange stripe.
On formal occasions, she wears a white t-shirt, a red dress with suspenders, and brown loafers. She wears this outfit with her pigtails.
In the summertime, Muffy wears a lavender t-shirt with a white collar, a green skirt with two pink stripes that are horizontal and vertical, and wears green flip-flops.
In "D.W. Blows the Whistle", Muffy wears an orange racing suit with a blue stripe, a white helmet, and orange sneakers.
In "Muffy's Art Attack", Muffy wears the first outfit that consists of a green and purple striped bodysuit, a purple puffy dress with green and purple pockets on the front, and black Mary Jane shoes. She wore this with her double braids and her pigtails. Muffy wears the second outfit that consists of a blue-collar shirt that has sleeves being rolled up above her elbows, white overalls, and brown dress shoes with brown laces. Muffy wears the third one consists of a yellow shirt, a salmon jacket over her shirt, a blue puffy skirt, blue tights, and black Mary Jane shoes. However, she still wears the second and third outfits in later seasons until Season 14.
In "Prunella Gets it Twice", Muffy wears her first outfit, but it has several color changes with her bodysuit having blue and yellow stripes, her dress being red, and her shoes being brown. The only hairstyle she can have with her first outfit with an alternate color scheme is her pigtails.
In "How the Cookie Crumbles", Muffy's third outfit is originally a blue dress and a white jacket over her dress.
In "Matchmaker, Match Breaker", Muffy wears a purple version of the third outfit, but the shirt is still yellow.
In Other Media
In the Living Books computer games, Muffy had a brown complexion, dark brown hair, and buck teeth in Arthur's Teacher Trouble. She subsequently had her complexion changed to pale, her hair color changed to light brown, and her buck teeth removed in Arthur's Birthday. It was likely due to color and tone restrictions during the 16-bit era of computers and software. Her vocal tone was a bit deeper, as she was voiced by Janice DeMichael Rogers before the cartoon show replaced her with Melissa Altro. In the later games, such as Arthur's Thinking Games, during the 32-bit era of computers and software, her appearance was the same as she looks in the cartoon show.
Throughout the series, Muffy had many alternate hairstyles. She gets her hair done for many occasions, and her favorite place to go hairdressing is the Salon de Beauté. Some of the episodes she is seen with different hairstyles include "Francine's Bad Hair Day", "Muffy's Art Attack", "Lights, Camera, Opera!", "The Lousy Week", "Don't Ask Muffy", "The Election" and "No Acting, Please".
Muffy often has a lack of empathy for everything and believes that money, Bailey, and her father can fix any problem. However, in some fields, Muffy is good at giving advice on things like fashion or love. She is usually the first one to catch on to a fad or a trend.
Like Arthur, she is 8 years old and in the third grade, but in contrast, she is fashionable, stubborn, beautiful, and very wealthy. She is often labeled a snob and spoiled because of her wealth, condescending attitude and frequent selfishness, as shown particularly in the episode "Spoiled Rotten". However, Muffy can be quite mature at times. Muffy is also shown to be quite popular, as shown by the many parties she hosts. Like her father, Muffy is also good at doing business with people. Despite all of that, Muffy has a knack for being friendly, cares a lot about her friends, loves to hang out with them, and they usually have a wonderful friendship. Muffy's spoiled home lifestyle has left her somewhat naive when it comes to certain basics of domestic life. She, for example, did not know how to wash dishes by hand in a sink, believing that she could get the job done simply by squirting some dishwashing liquid on a pile of dirty dishes sitting in a sink. ("The Great MacGrady")
Despite having a huge mansion, Muffy's family is quite small. She lives with her Father (Ed Crosswire), her mother (Millicent Crosswire), and her butler (Bailey). Like D.W., she refers to her parents as "Mommy" and "Daddy". Muffy has an older brother named Chip, who was first referred to in Arthur's Perfect Christmas, but did not appear until "Matchmaker, Match Breaker".
- Francine Frensky - Muffy's best friend. Though they are different in numerous ways, they always manage to find something to do together, such as in the episode Muffy's New Best Friend. The girls met when Muffy moved to Lakewood when they were both in second grade. They got to know each other better when they found out that they had the same middle name, "Alice." Despite their frequent arguments, the two girls do truly value each others friendship and care about each other deeply. This can be seen the episode "Vomitrocious" were Muffy showed genuine concern over Francine's well being and health.
- Fern Walters - Muffy and Fern did not frequently do things together in the earlier episodes, excepting Muffy's sleepovers. One episode, however, that Muffy and Fern got along is "Phony Fern", where they are seen hanging with each other by watching a movie and talking to each other on the phone.
- Prunella Deegan - Muffy and Prunella are seen together when they shop and have sleepovers and when there is an event at school or anything formal. In "Sue Ellen Moves In", it is mentioned by Arthur that Muffy did not immediately take to Prunella, befriending her only after a period of dislike.
- Arthur Read - Muffy and Arthur are great friends. They both have the same birthday: May 25. Arthur tends to get annoyed when Muffy talks about shopping and playing with her Polly action figures. But despite all of that, they are still great friends.
- Buster Baxter - Muffy and Buster are good friends. Muffy is usually disgusted of Buster's unhealthy eating habits, such as expired food or food that was dropped on the floor. Like Arthur, he also tends to get annoyed when Muffy talks about shopping and how popular she is. But despite that, they are still good friends.
- Kaylie Lamott - Kaylie is a girl that Muffy met when she was staying at a shelter for residents of Elwood City that were displaced by Hurricane Sadie. Muffy was initially appalled at the idea of staying at a shelter, which only happened when there was a mistake with her family's reservation at a 4-star hotel and they were unable to find other lodgings. Kaylie gave Muffy advice on how to find the best snacks at the shelter and how to block out the sounds of snoring. The two quickly became friends and played together. Muffy was shocked when she learned that Kaylie's home had been almost completely destroyed by the storm and offered her and her mother a room at the Crosswire Estate. The two had already made the decision to move in with Kaylie's uncle in Florida, but before they left, Muffy and Kaylie spent time together in the repaired Ice Cream Shop.
Muffy is also friends with Brain, Binky, Jenna, and Sue Ellen. In "The Trouble with Trophies", Muffy's relationship with George seems to have grown. They agree to work together to try and give Fern a trophy. Muffy wasn't exactly friends with George in past episodes but she is now. However, she made fun of him in "Vomitrocious!" and he is often forgotten by the main group of friends.
Muffy is also close to her butler, Bailey. He performs her every order, and sometimes advises her, as well. In "The Butler Did... What?", Muffy realized she did not know anything about Bailey and was very hurt when she believed that Bailey had run away. In the conclusion, she shows a considerate facet of herself and vows to learn everything about her butler.
- It is revealed in "Muffy's Soccer Shocker" that in a possible future, well after the events depicted in normal episodes of the series, Muffy has a son who takes after her.
- Her speaking debut was also in "Arthur's Eyes" and her first line was "How do you get in trouble with the nurse?"
- Muffy had two front buck teeth from the episode "Arthur's Eyes" to "Arthur, World's Greatest Gleeper". It was also shown in "The Scare-Your-Pants-Off Club!", but they would disappear in some scenes.
- Muffy's first hairstyle was seen in "Francine's Bad Hair Day". The style was called "Prom Queen" by her hairdresser.
- Muffy is one of the few characters on the show with cell phones. Not only does she stand out in her mere possession of a cell phone, but she also has more than one. Its first appearance was in Francine's Bad Hair Day, her second in "Fernfern and the Secret of Moose Mountain", her third in the first part of "Phony Fern", and her fourth phone (Portalex 360) also in "Phony Fern". Every single one has been a flip phone.
- It has been stated that Muffy takes tap and ballroom dancing classes after school.
- Muffy's quote "Vomitrocious" first appeared in the book Arthur's Thanksgiving, but became more and more common in the cartoon.
- There are at least eight episodes that have Muffy's name in the title.
- Muffy has been voiced by Melissa Altro since the first season. Altro is the only voice actor to begin voicing their character as a child and continuing to do so as an adult (she was 13 when she began voicing Muffy). If one listens carefully, one can tell Muffy's voice differs across seasons, sounding higher-pitched in the earlier ones.
- In "Poor Muffy", she is revealed to be allergic to the odors of new carpets her family was once putting into their mansion but began removing when they learned about her allergies.
- During formal occasions, she sometimes had her frontal hair cut into bangs.
- Muffy and Francine have the same middle name, Alice.
- She is the substitute (and relatively unskilled) goalkeeper for the Lakewood Elementary Soccer Team.
- In "The Contest", the last scene parodies the teenagers in That 70's Show. Muffy seems to represent Donna.
- Also for the Lakewood Elementary Soccer Team, she is their cheerleader.
- Muffy is somewhat spoiled. In "My Club Rules", she kicked Francine out of her club for not showing up on one day because she was sick.
- Her Dad likes to refer to her as "Muffin."
- She is called 'Molly' in the French Canadian dub of the show. .
- Her character as created by Marc Brown is based on his sister Bonnie's best friend when she was growing up.
- In "The Scare-Your-Pants-Off Club!" it's revealed that eating Hasenpfeffer Ice Cream gives her nightmares.
- Season 1
- Arthur's Eyes 101a
- Francine's Bad Hair Day 101b
- Arthur and the Real Mr. Ratburn 102a
- Arthur's Spelling Trubble 102b
- D.W. All Wet 103a
- Buster's Dino Dilemma 103b
- D.W.'s Imaginary Friend 104a
- Arthur's Lost Library Book 104b
- Arthur's Pet Business 105a
- D.W. the Copycat 105b
- Locked in the Library! 106a
- Arthur Accused! 106b
- Arthur Goes to Camp 107a
- Buster Makes the Grade 107b
- Arthur Bounces Back 108b
- Arthur's Birthday 110a
- Francine Frensky, Superstar 110b
- Arthur's Baby 111a
- Arthur Writes a Story 112a
- Arthur's Lost Dog 112b
- Buster's New Friend 113b
- Arthur and the True Francine 114b
- Arthur and the Crunch Cereal Contest 116a
- Meek for a Week 117a
- Arthur, World's Greatest Gleeper 117b
- Arthur's Chicken Pox 118a
- D.W. Rides Again 119a
- Arthur Makes the Team 119b
- Arthur's Almost Boring Day 120a
- Sue Ellen Moves In 121a
- Team Trouble 122b
- Bully for Binky 123a
- Misfortune Teller 123b
- Arthur's Tooth 124a
- Arthur Cleans Up 125b
- My Dad, the Garbage Man 126a
- Poor Muffy 126b
- D.W.'s Blankie 127a
- Arthur's Substitute Teacher Trouble 127b
- I'm a Poet 128a
- The Scare-Your-Pants-Off Club 128b
- My Club Rules 129a
- Stolen Bike 129b
- Season 2
- Lost 209a
- Season 5
- Season 8
- Castles in the Sky 901a
- Tipping the Scales 901b
- Francine's Big Top Trouble 902a
- George Blows His Top 902b
- Arthur Weighs In 903a
- The Law of the Jungle Gym 903b
- Buster's Green Thumb 904a
- Lights, Camera... Opera! 905a
- All Worked Up 905b
- Arthur Makes Waves 906a
- Three's a Crowd 907a
- A is for Angry 907b
- The A Team 908a
- Binky Goes Nuts 910a
- Breezy Listening Blues 910b
- Happy Anniversary 1001
- Fern and Persimmony Glitchet 1002b
- Desert Island Dish 1003a
- Feeling Flush 1004a
- Family Fortune 1004b
- Flaw and Order (prologue) 1005b
- The Curse of the Grebes 1006a
- Unfinished 1007a
- D.W., Bossy Boots (Cameo and prologue) 1007b
- Binky vs. Binky (cameo) 1008a
- Do You Speak George? 1009a
- World Girls 1009b
- What's Cooking? 1010a
- Buster's Special Delivery 1010b
- Season 11
- Season 12
- Season 13
- Brain Sees Stars 1901b
- Sue Ellen Adds It Up 1902a
- Wish You Were Here 1902b
- Arthur's Toy Trouble 1903a
- Spar for the Course 1903b
- Dueling Detectives 1904b
- Maria Speaks 1906a
- Postcards from Binky 1906b
- Carl's Concerto 1907a
- Too Much of a Good Thing 1907b
- Francine's Cleats of Strength 1908a
- Little Miss Meanie 1908b
- Mr. Ratburn's Secret Identity 1909a
- Besties 1909b
- The Last Day 1910
- Season 20