The Underwearwolf

by Gideon Sterer, Charles Santoso (Illustrator)

Perfect for fans of Creepy Pair of Underwear, this wolfish picture book romp follows a kid who finds himself in a hairy situation when he dons a pair of not-so-normal undies under the light of the full moon.

Do not, under any circumstances,
Or for any reason,
Wear this underwear under the full moon.

Do you understand?

Get ready to howl with laughter as one rule-breaking, underwear-loving kid transforms into a—gasp!—UNDERWEARWOLF! Now he’s on an unforgettable nighttime adventure that may or may not include furry paws, sharp claws, uncomfortable wedgies, and an honest-to-goodness wild wolfpack! No butts about it—this is one read-aloud that’ll blow your undies off!

Genres: Picture Books, Childrens, Fiction, Humor, Halloween, Monsters

32 pages, Hardcover

Published May 12, 2026

Reviews

[Little Batties · Rating 5 out of 5]

The Underwearwolf is a clever and humorous twist on a classic movie monster. Gideon Sterer has brought to life a hilarious and furry new friend kids are sure to love.

Our main character LOVES underwear. He has a collection he is clearly proud of, so when his uncle gives him a special pair for his birthday, he cannot wait to try them on. Sadly, he does not heed the warning written on the fine print of his underwear. It devolves into a hair-raising tale about a little underwearwolf as he ventures around town under the light of the full moon.

It has beautiful illustrations, carefully crafted to delight and capture the attention of its readers. This is the kind of story that will draw the readers in, having them hanging on each page until the very end. I would definitely recommend this for anyone looking for a cute Halloween story to share with littles; it definitely has the potential to become a spooky season favorite in and out of the classroom.

Thank you NetGalley and Simon and Schuster Children's Publishing for giving me an advanced copy of this book in exchange for an honest review.

[Melanie Hetrick · Rating 4 out of 5]

A young boy receives a pair of strange underpants for his birthday. He loves underwear and can't wait to try these on. He chooses to ignore the warning not to wear them during a full moon. That decision make for a very interesting night including fangs, claws and actual wolves!

Hilarious! Recommended for storytime.

[Tonja Drecker · Rating 5 out of 5]

This little boy really likes his underwear. He even has a pair hung up for each day of the week. So, when a relative gives him an unique pair of wool, fuzzy underwear, the boy is excited...although even he finds fuzzy underwear a bit odd. Stranger yet, there's a note on the inside, which warns from wearing the underwear during the full moon. The boy doesn't care about that, though, and quickly puts them on. The last thing he expects is to turn into a werewolf and take off into the night.

While I thought this would be an 'underwear humor' read...and it is that too...but it swings into the wilder side with the werewolf adventure, too. The boy is introduced with a bit of an oddity as very colorful underwear hang, each with its own hanger, along a wall. So while there is underwear humor, it comes with a little edge to keep it more subtle and run right along with the paranormal side. This makes it even a nice read for Halloween as the boy takes off into the night and meets more monsterly-ish adventures there. This side has a racing feel to it and keeps a slightly tense action style Then, there's a little uncertainty as the boy wonders if everything is getting to be too much, but that's exactly when the author tosses in a phrase of humor, which adds a giggle of lightness despite the whisper of something heavier.

The illustrations match the mood changes wonderfully and go from light silliness to dim and spooky. It creates a grabbing read and works well for read-aloud sessions or for listeners to explore on their own.

[Heidi · Rating 4 out of 5]

A young boy receives an awesome pair of underwear for his birthday. Bright yellow and made of wool, he is excited to wear them. But they come with a warning not to wear them during the full moon. But the boy looks out the window and decides it's too full (it's clearly the full moon!). After putting on the underwear the boy turns into the Underwearwolf and takes off into the city where he causes trouble (tearing up plants, knocking over garbage cans, destroying bird feeders, and other acts of a wild animal. He thinks about taking off the underwear but doesn't want to be 'butt naked' where anyone could see him. Even a wedgie doesn't slow him down much especially once he meets a pack of wolves. As dawn approaches he returns home where he is finally comfortable enough to remove the underwear. Note : the boy is shown with no clothes on but from the side (his private parts are not shown in the illustration). The silliness of the story as well as the title are bound to appeal to many young readers. The out-of-control behavior of the boy as the underwearwolf will appeal to children who love the No, David books by David Shannon, or other stories with 'wild' behavior. Will the book inspire children to behavior out-of-control themselves? Most likely not. Will they want to pretend to be an underwearwolf themselves? Possibly. A fun book for young readers who enjoy outrageous stories with wild adventures. Recommended.

[Kelly · Rating 5 out of 5]

We read Underwear Wolf and thought it was absolutely hilarious—we definitely recommend it! From the very beginning, it had us laughing, and honestly, we didn’t want it to end. We are already hoping there will be another book so we can find out what Underwear Wolf does next!

One of our favorite parts was all the tiny, funny details in the illustrations—like the underwear on the curtains. It made us want to look closely at every page because there was always something new to notice.

We also loved the word choice in the story. Words like menace and maniac made it even funnier and helped bring the character to life. The running joke about how he couldn’t take the underwear off because he would be butt-naked made us laugh every single time.

The way the author used ALL CAPITAL LETTERS added so much energy and excitement to the story, and the different sections and layouts on each page made it really fun to read.

Overall, we couldn’t stop laughing, and this book is one we would read again and again. If you like silly, creative, and slightly mischievous stories, this is a must-read!

Reviewed by Chappell Elementary 4th graders

[Sandra Stiles · Rating 5 out of 5]

Are you looking for something fun to read to or with your child? This is an awesome book. Take one young birthday boy, a gift from his uncle and get ready for a fun read.

The main character is a young boy who has just received the strangest pair of underwear from his uncle. They are made of wool. Not only are they made of wool, they come with a warning about not wearing them on a full moon. Of course he puts them on. After turning into an underwearwolf he goes on an adventure into the night. This was such a strange and original idea that I laughed and laughed. Along with such an awesome story, you have wonderful pictures from Charles Santoso. The repetition of the phrase "I should have taken them off, but then I would have been butt naked..." cracked me up. I have great-grandson who would love this fun book. We definitely need more books like this. Reading needs to become fun again and it needs to begin with the youngest readers. I can say I highly recommend this book to parents and grandparents, or people like me who love books for all ages.

[Katie · Rating 4 out of 5]

"The Underwearwolf" follows a young boy as he experiences the effects of his new, supernatural underwear. This was a comical children's book that I think a lot of kids will enjoy, especially ones who like a bit of monster "spook" (and what kids don't get a laugh out of underwear?). It was reminiscent of "Creepy Pair of Underwear" which my preschool class adores, so I know they'd be huge fans of "The Underwearwolf" as well.
I'd recommend this book for children ages 3.5-5 years of age.

Thank you, Simon and Schuster Children's Publishing, for the advanced e-copy in exchange for my honest review.

[Molly · Rating 5 out of 5]

I received a free eARC from NetGalley in exchange for an honest review. This would be an EXCELLENT choice for an elementary school field trip! It's probably a little over the heads of our toddler/preK crew, but I think 7 year olds would find it utterly hilarious. It's about a pair of underwear that turn the main character into...a werewolf. He spends the night wreaking all kinds of havoc, and frequently thinks to himself that he ought to take them off. But then he would be butt naked! I can already hear the giggles.
(it's also a good companion to Creepy Pair of Underwear, obviously!)

[ElfElm Publishing · Rating 5 out of 5]

"The Underwearwolf" is hilarious and features a wonderful story and talented artist. A good read for kids and anyone with a sense of humor. The title drew me in, but the art kept me excited to keep turning pages to see more. The concept is fun and simple: don't wear the underpants on a full moon or you'll turn into a werewolf! Of course the drawers are worn on a full moon, and shenanigans ensue. Delightful!

Thanks SimonKids for the ARC! :)

[Erika · Rating 4 out of 5]

Who doesn't love a good story featuring UNDERWEAR? This book will make you laugh out loud, and it will be the perfect gift for that kid in your life who starts giggling at the sound of certain words... like underwear! A laugh-out-loud book, perfect for Halloween but also a book that can be enjoyed all year round.

[Ambi · Rating 4 out of 5]

What’s not to love about this book? Werewolves and underwear collide in this charming, clever picture book. My kids thought it was hysterical and just the right amount of spooky.

Thanks to NetGalley and the publisher for the ARC!

[Michele Knott · Rating 4 out of 5]

Whenever I find a book that I know is going to make kids laugh, it's like I found treasure. These are the books you know you'll get readers for.
This one mentions underwear and the word "butt" in many formats. Yup. Kids will love it.

[Raven Black · Rating 3 out of 5]

If you like underwear humor, this is the book you need. The illustrations are fun. Read via an online reader

[Sarah Threlkeld · Rating 5 out of 5]

F & G review: I cackled while reading this. Huge kid appeal!

[Carol Gordon Ekster · Rating 4 out of 5]

Humorous, creative, and great illustrations.

[Lisa Davidson · Rating 5 out of 5]

This is so completely and perfectly hilarious. Who would have thought of combining underwear and werewolves? Comic genius! This is real adventure.
Thanks to NetGalley for letting me read this

[Brenda]

Review closer to release

[Mompop · Rating 4 out of 5]

did not see this option when I was buying "underoos" for my son

[Taylor Woolley · Rating 5 out of 5]

So funny! Perfect bedtime story for spooky season (or any other time of the year).

[Fabre Brooks · Rating 5 out of 5]

Humorous, silly, goofy fun! I loved it. Read to my 33 years old partner. We were giggling! Great illustrations.

[Heidi Yates · Rating 4 out of 5]

Word of warning: This is a hair-raising tale about a supernatural pair of underpants. Read at your own peril, laughter may ensue. Haha!

[Beth · Rating 4 out of 5]

What fun! Children will love this, and so will the older humans who read this to them!

[ava · Rating 4 out of 5]

very fun!

[Mary · Rating 4 out of 5]

I have no doubt this will be a storytime hit with K-2nd graders.