Big Mouth Monster
Big Mouth Monster
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Big Mouth Monster
Most Halloween costumes get worn once and shoved in a closet. This one ends up on your couch every night from October through February.
The Big Mouth Monster is a hooded plush fleece onesie with an oversized toothy mouth — a proper costume at a party, and genuinely wearable loungewear the rest of the year. Soft fleece throughout, roomy enough to pull on over what you're already wearing, and warm enough that you'll stop reaching for a blanket.
Seven colors, seven creatures
- Swamp Gremlin — Green
- Midnight Creep — Black
- Witching Hour — Purple
- Bedsheet Ghost — White
- Moonlit Chill — Blue
- Devil's Due — Red
- Pumpkin Patch — Orange
Available in sizes S, M, L, XL and XXL.
Why it stays in rotation
- A costume that doubles as loungewear — the cost per wear beats anything from a seasonal pop-up shop
- Hooded, so the character reads instantly in photos
- Plush fleece that stays soft wash after wash
- Seven colors means a whole group can match without wearing the same thing
Free shipping within the US. Orders ship within 1–2 business days — if you're buying for Halloween, order by early October to be safe.
“I ordered the purple one in a size L and it fit exactly how I hoped—roomy enough to move around in without looking oversized. The big mouth design is hilarious in person, and everyone kept asking where I got it. Easily the most fun Halloween costume I’ve bought.”
Why You'll Love It
Why You'll Love It
Most Halloween costumes are one uncomfortable night in scratchy polyester. This isn't that.
It's a full-body plush onesie with an oversized monster head, googly eyes, and a mouth big enough to be seen across a room. Soft fleece throughout, roomy enough to layer over normal clothes, and warm enough that you'll actually want to keep it on all night.
Then it becomes your winter pajamas. Seven colors — pick your monster.
What's Included
What's Included
1 × Big Mouth Monster costume with attached hood
1 × pair of matching monster feet
1 × Comb
Materials & Sizes
Materials & Sizes
Fabric: 100% polyester coral fleece, 251–300 GSM — thick, plush, and genuinely warm
Design: Full-body onesie with attached monster hood and front belly pocket
Fit: Relaxed, oversized, unisex — designed to layer over regular clothes
Available sizes:
S — 4'11"–5'1" (150–155 cm), 88–110 lb
M — 5'1"–5'5" (155–165 cm), 110–143 lb
L — 5'5"–5'9" (165–175 cm), 143–176 lb
XL — 5'9"–6'1" (175–185 cm), 176–198 lb
Between sizes, or over 5'10"? Size up. Arms and legs run short on one-piece costumes.
Care: Machine wash cold on a gentle cycle. Air dry or tumble dry low. Do not bleach or iron — high heat flattens the pile.
Shipping & Returns
Shipping & Returns
Shipping: At Gloomberry, we're committed to fast and reliable service. Orders are processed within 24–48 hours (excluding weekends and holidays) and usually arrive within 3–7 business days.
Returns: If you're not fully satisfied with your purchase, we offer a 30-day return, exchange, or replacement policy to make sure you're happy. Items returned after this period will be sent back to you.
Costume by Night. Pajamas Forever.
Most Halloween costumes get worn once, then spend the rest of their life shoved in a closet. Not this one. The Big Mouth Monster Onesie is the costume your family will fight over on October 31st — and live in every movie night, lazy Sunday, and cold evening after. Ultra-soft premium fleece, a full-coverage monster hood, and a design silly enough to make everyone smile. Halloween is one night. Cozy is forever.
You Won't Get Through The Door Unnoticed
Everyone else came as a vampire. Again. You came as a seven-foot plush monster with a mouth the size of a dinner plate — and you're the one in everybody's camera roll.
Seven colors. Grab a friend and go as a pack.
11.294 People are Ready for Halloween!
Excellent 4.8 / 5
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So much fun
“Wore this to a Halloween party and everyone loved it. The costume is hilarious in person and really comfortable too.”
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Great fit
“I ordered the red one in medium and the fit was just right. It was easy to move around in and got a lot of laughs.”
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Exactly what I wanted
“The blue costume looked even better in person. I’m usually between sizes, so I ordered a large for a looser fit and it worked perfectly. Definitely wearing it again next Halloween.”
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Everyone wanted pictures
“I wore the green one to a costume party and people kept stopping me for photos. It’s silly in the best way and surprisingly comfortable for something this big. I’m really happy with it.”
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Best costume at the party
“I ordered the orange costume in XL because I wanted enough room to wear clothes underneath. It fit comfortably and didn’t feel restrictive at all. The big mouth and eyes looked so funny when I moved around, and my friends couldn’t stop laughing. Easily one of the most memorable costumes I’ve worn.”
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Ordered another color for my brother
“I originally bought the purple one in size L for myself, but my brother liked it so much that we ordered him the black version too. The costumes were comfortable, easy to put on, and looked great in photos. We wore them together to a Halloween event and got compliments all night. Such a fun choice if you want something different from the usual costumes.”
