Last updated: April 26, 2026· By Seckin Peker

Costume Guide

Boo Halloween Costume Guide

Monsters, Inc.  ·  Pixar  ·  2001

Kitty! Pink dress, purple leggings, white socks, butterfly hairbands, and the boundless, fearless delight of the only human child who has ever looked at a nine-foot-tall monster and decided it was a kitty. She was not wrong.

Disney Monsters, Inc. Cartoon Short Hair
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Quick Answer: To dress like Boo from Monsters, Inc., put on the dark rose pink t-shirt dress over the light purple seamless leggings, pull on the white ankle socks, and use the butterfly ball hairbands to style the hair into two small pigtails sitting close to the head. That is the entire build — five pieces, no makeup beyond a natural look, no wig required. The pigtails are the most important styling detail: Boo’s hair sits in two small, slightly uneven bunches rather than neat or high ponytails, and getting that specific small-and-low quality right is what makes the silhouette read as Boo rather than as a generic pink dress. For younger wearers, the dedicated Boo toddler costume is available as an all-in-one option.

Boo — her real name is Mary, though this is only briefly revealed in the film — is the human toddler at the heart of Monsters, Inc., the 2001 Pixar animated film directed by Pete Docter. She wanders through a closet door into the monster world and ends up in the care of James P. Sullivan, the Monsters, Inc. top scarer, whom she immediately names “Kitty” and follows with the complete, unselfconscious trust of a child who has not yet learned to be afraid of large furry things. Her voice was captured by following actress Mary Gibbs around with a microphone rather than having her record scripted lines, giving Boo’s dialogue its genuinely irreproducible quality of real childhood spontaneity. She is one of Pixar’s most beloved characters, the emotional core of one of the studio’s most affecting films, and her costume is one of the simplest and most immediately recognisable character builds available from any animated film in the studio’s catalogue.

Items Total5 Items
DifficultyEasy
Film2001
Cost$30–$60

Boo Costume Items

Numbered Boo Monsters Inc Halloween costume shopping infographic showing five labeled items: dark rose t-shirt dress, light purple seamless leggings, white ankle running socks, butterfly ball hairbands, and Boo toddler costume

Boo Costume Items — Monsters, Inc.

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Boo Monsters Inc Pixar Halloween
  • 1 Dark Rose T-Shirt DressDark rose pink short-sleeved t-shirt dress forming the entirety of Boo’s upper and lower costume, the single most important piece in the build and the colour that makes the character immediately recognisable from any distance
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  • 2 Light Purple Seamless LeggingsLight purple leggings worn beneath the pink dress, completing Boo’s two-tone colour palette and visible below the dress hem — the purple and pink combination is the costume’s entire colour scheme and both pieces must be present for the look to read correctly
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  • 3 White Ankle Running SocksWhite ankle socks completing Boo’s look from the ankle down, worn over the leggings and visible above any footwear — the clean white provides the only neutral tone in an otherwise fully pink-and-purple costume
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  • 4 Butterfly Ball HairbandsButterfly ball hairbands used to style the hair into Boo’s signature two small pigtails, the accessory that most immediately identifies the character’s silhouette and the most important styling detail in the entire build
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  • 5 Boo Toddler CostumeDedicated all-in-one Boo toddler costume, the most straightforward option for younger wearers and ideal for family group builds alongside adult Sulley and Mike Wazowski costumes
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Boo from Monsters Inc wearing her monster disguise costume — the pink one-eyed monster suit Sulley and Mike use to sneak her through Monsters Inc headquarters, showing the adorable disguise scene from the film

How to Style the Boo Costume

The Boo build is the simplest in this guide’s catalogue: put on the purple leggings, pull the dark rose dress over them, pull on the white ankle socks, and style the hair into two small pigtails with the butterfly hairbands. The entire assembly takes under ten minutes. The only detail that requires attention is the pigtails — their position, size, and style are what convert a pink dress into Boo specifically — and a single minute spent getting them right before leaving is the difference between the costume working immediately and requiring explanation. For makeup, Boo’s look is no makeup at all: a clean, natural complexion consistent with a toddler who has not yet encountered cosmetics and is currently too busy pointing at monsters to consider the matter.

The Pigtails: Getting Boo’s Specific Hair Right

Boo’s pigtails are the most important single styling element of the costume and the detail that most clearly distinguishes the build from a generic pink dress. The key qualities: small, low, and slightly uneven. Her pigtails sit close to the head rather than high on the crown, are small in volume rather than full, and have a slightly casual positioning that reflects a toddler’s hairstyle rather than a deliberate adult styling choice. Position the butterfly hairbands at approximately ear level or just below, gathering a small amount of hair on each side. If the hair is too long to sit in small pigtails without the excess hanging below the band, two small buns are an acceptable variation — the silhouette from a distance reads the same. If natural hair is very short or shaved, two small clip-in sections of dark hair attached with butterfly clips at ear level replicate the effect. The pigtails should be checked in a mirror from a distance of at least a metre before leaving, since they read from across a room rather than up close.

Making the Boo Costume Work for Adults

The Boo costume translates directly to adult wearers without modification — the same five pieces, assembled in the same way, produce the same immediately recognisable character. The one adjustment worth making for an adult build is shoe choice: clean white trainers or simple white canvas shoes worn over the white ankle socks reinforce the colour palette and sit naturally with the casual aesthetic of the costume. Avoid heels or formal shoes, which shift the costume’s register away from the character’s specific childlike quality. For events where the costume needs to be worn for an extended period, the seamless leggings and t-shirt dress combination is one of the most comfortable character builds available — there are no structured pieces, no restrictive elements, and no accessories that require maintenance throughout the evening. The only thing to check periodically is the pigtails, which can loosen during movement and should be re-secured with the butterfly bands if needed.

Boo Group Costume Ideas

The Monsters, Inc. Family

Boo, James P. Sullivan, Mike Wazowski & Roz

The central cast of Monsters, Inc. assembled as a group, covering every register of the film’s world in a single ensemble. Boo’s tiny pink dress alongside Sulley’s enormous blue-and-purple fur suit — the most immediately size-contrasting costume pairing available from any animated film — Mike Wazowski’s single green eye and compact round body, and Roz’s slug-like administrator aesthetic create a group with extraordinary visual variety and a shared identity that every Pixar fan will recognise instantly. The Boo-and-Sulley pairing at the centre of the group is the emotional core of the film translated directly into a costume dynamic: the enormous monster and the tiny child who called him Kitty, with complete sincerity, and was not remotely wrong. The group works at any event size and rewards a multigenerational audience equally well.

Boo James P. Sullivan Mike Wazowski Roz

Iconic Cartoon Girls

Boo, Abby Park, Star Butterfly & Lucy van Pelt

Four beloved animated girls from across four decades and four distinct animation traditions, united by the quality of being characters who are exactly and entirely who they are without apology or modification. Boo’s pink toddler energy, Abby Park’s Big City Greens confident cheerfulness, Star Butterfly’s interdimensional princess chaos in her pink dress, and Lucy van Pelt’s Peanuts-era brown coat and furious certainty about everything create a group with strong visual variety and a shared register of animated girls who occupy their respective shows with complete self-possession. The group rewards a broad animation audience and works well as a celebration of the animated girl character across different eras and styles of children’s television and film.

Boo Abby Park Star Butterfly Lucy van Pelt

Adventurous Animated Girls

Boo, Eliza Thornberry, Dora the Explorer & Izzy

Four animated girls from children’s television defined by curiosity, bravery, and a shared tendency to end up in extraordinary situations and treat them as entirely normal. Eliza Thornberry’s safari gear and red hair from The Wild Thornberrys, Dora’s explorer backpack and boots, and Izzy’s Jake and the Never Land Pirates gold streak and pixie wings alongside Boo create a group united by the specific animated girl archetype of the fearless child explorer — characters who encounter the extraordinary and run toward it rather than away. The group works at any event size, spans multiple generations of children’s television fans, and produces a clear shared identity that rewards anyone who grew up watching any of the four shows.

Boo Eliza Thornberry Dora the Explorer Izzy

Animated Best Friends & Sidekicks

Boo, Fionna, Dee Dee & Isabella Garcia-Shapiro

Four animated girls who share a specific quality: they make every scene they are in more fun, more colourful, and more emotionally generous, and the shows they appear in are significantly better for their presence. Fionna’s Adventure Time adventurer look with her white bunny hat and blue dress, Dee Dee’s Dexter’s Laboratory pink tutu and boundless physical enthusiasm, and Isabella Garcia-Shapiro’s Fireside Girls uniform and patient, capable cheerfulness from Phineas and Ferb alongside Boo create a group that rewards any dedicated animation fan across multiple Cartoon Network and Disney Channel generations. All four characters share a genuine warmth that makes the group as enjoyable to be part of as to look at, and the variety of their visual identities ensures each person in the group is clearly distinct and equally recognisable.

Boo Fionna Dee Dee Isabella Garcia-Shapiro
Celebrity family Halloween costume: Scheana Shay dressed as Mike Wazowski, her husband Brock Davies as Sulley, and their daughter Summer as Boo from Monsters Inc — showing the complete Monsters Inc family group costume in action

Boo Costume — Frequently Asked Questions

Boo wears a dark rose pink short-sleeved t-shirt dress, light purple leggings, white ankle socks, and two small pigtails held with butterfly ball hairbands. The pink-and-purple two-tone palette is the costume’s entire colour scheme, and both pieces must be present for the look to read correctly. A dedicated Boo toddler costume is available as an all-in-one option for younger wearers. The build requires no makeup, no wig, and no specialty purchases — just the five listed pieces assembled correctly.

Boo — real name Mary — is the human toddler at the centre of Monsters, Inc., the 2001 Pixar film directed by Pete Docter. She wanders through a closet door into the monster world and ends up in the care of top scarer James P. Sullivan, whom she immediately names “Kitty.” Her voice was captured by following actress Mary Gibbs around with a microphone rather than scripted recording sessions, giving Boo’s dialogue its specific quality of genuine childhood spontaneity. She is one of Pixar’s most beloved characters and the emotional centre of one of the studio’s most affecting films.

Boo’s most famous and most quoted line is her delighted “Kitty!” directed at Sulley throughout the film — delivered with the complete unselfconscious enthusiasm of a toddler who has decided a nine-foot-tall furry monster is her favourite thing and sees no reason to reconsider. Her giggling and toddler babble are as iconic as any specific line, since the film’s emotional weight rests on the fact that Boo communicates primarily through laughter and the brightness of her attention rather than through dialogue. For in-character use at a Halloween event, pointing at anything large and furry and shouting “Kitty!” is the complete Boo moment and needs no explanation for anyone who has seen the film.

Yes — Boo is one of the most straightforward animated character builds available, requiring only five pieces: a dark rose t-shirt dress, light purple seamless leggings, white ankle socks, and butterfly ball hairbands for the pigtails. A dedicated toddler costume is also available as an all-in-one option for younger wearers. The build requires no makeup, no wig, and no specialty items. Total cost typically runs $30 to $60, making it one of the most budget-friendly recognisable character costumes available from any Pixar film.

Monsters, Inc. is a 2001 Pixar animated film directed by Pete Docter, set in a world where monsters power their city by harvesting the screams of human children through closet doors. The Monsters, Inc. top scarer, James P. Sullivan, and his partner Mike Wazowski must return a human child — Boo — to her world after she accidentally enters theirs, while evading their colleague Randall and ultimately discovering that children’s laughter is far more powerful than their screams. It is widely regarded as one of Pixar’s finest productions. A prequel, Monsters University, was released in 2013.

Boo and Sulley’s relationship is the emotional core of Monsters, Inc. Sulley — initially panicked by her presence in the monster world — gradually becomes her protector over the course of the film, driven by Boo’s complete and unconditional trust in him. Her calling him “Kitty” and following him with fearless affection is what ultimately transforms him morally. The film’s final scene, in which Sulley opens Boo’s reconstructed door to find her waiting, remains one of the most celebrated emotional payoffs in Pixar’s history and the reason the Boo-and-Sulley group costume is one of the most affecting parent-and-child Halloween builds available from any animated film.