The Monster Onesie in Swamp Green — oversized big mouth fleece monster onesie, front view
The Monster Onesie in Swamp Green — big mouth fleece monster onesie
Adult and kids Monster Onesies in Swamp Green together — matching family Halloween onesies
Swamp Green and Butterscotch Monster Onesies together — matching couples Halloween onesies
Swamp Green Monster Onesie worn with a friend — matching monster onesies for couples
All eight Monster Onesie colors together — group Halloween onesies for friends and family
The original big-mouth

The Monster Onesie

$54.99

Free shippingMix colors & sizes

Sizes run small — pick by height, or open the size guide.

Sizes run small — pick by height, not the letter.

  • S — 4'11″–5'1″ (150–155cm) · 88–110 lb
  • M — 5'1″–5'5″ (155–165cm) · 110–143 lb
  • L — 5'5″–5'9″ (165–175cm) · 143–176 lb
  • XL — 5'9″–6'1″ (175–185cm) · 176–198 lb

Between sizes? Size up.

The Monster CombIncluded free with the Monster Onesie
Free gift

Arrives in 7–14 days · 30-day returns
Description

A big fleece monster with an enormous mouth and eyes that don't quite agree with each other. You will look ridiculous — that's the entire point.

Oversized through the body, long in the arm, built to be lived in rather than worn. Soft coral fleece and a pocket with a small face on it.

Buy two and match with someone. Buy four and ruin a group photo properly.

Fit & fabric

Sizes run small — pick by height, not the letter.

  • S — 4'11″–5'1″ (150–155cm) · 88–110 lb
  • M — 5'1″–5'5″ (155–165cm) · 110–143 lb
  • L — 5'5″–5'9″ (165–175cm) · 143–176 lb
  • XL — 5'9″–6'1″ (175–185cm) · 176–198 lb

Between sizes? Size up — it's meant to swallow you.

Care

Cold wash, low tumble, don't iron the face.

Comes out of the machine fluffed and ready for another week of not being taken off.

Shipping & returns

Free US shipping on orders over $60. Orders typically arrive within 7–14 days, with tracking from the moment they ship.

30 days to decide. Send it back within 30 days of delivery — no forms, no interrogation, no hard feelings.

See it move

Fleece in motion.

day 6: still on
the group chat reacts
wash 4, still fluffy

The people have spoken. Mostly in caps.
More monsters

There are others.

See the whole lot →
The Dinosaur Skeleton in Grey — plush dinosaur skeleton costume with skull hood and spine, side view The Dinosaur Skeletonfrom $47.99 The Bunny Onesie in Marshmallow — oversized coral fleece bunny onesie for adults, front view The Bunny Onesiefrom $59.99 The Fang Onesie in Cream — fleece monster onesie with pointed ears and fangs, front view The Fang Onesiefrom $59.99 The Shark Onesie — two-tone grey fleece shark onesie for adults, front view The Shark Onesiefrom $59.99