The following is a list of characters from It Came from Beneath the Sink! and its television adaptation in order of appearance.

This page contains spoilers! Do not read this before finishing the story.


Character Medium Description
Katrina "Kat" Merton

Book and TV episode The protagonist and narrator of the book. She has lots of freckles and reddish hair that she wears in a ponytail. When Kat and her family move into a new home, they find a strange sponge-like creature under the sink, and that creature is starting to bring bad luck to the Merton family.
Mr. and Mrs. Merton

Book and TV episode The parents of Kat and Daniel Merton. Mr. Merton resembles his daughter, while Mrs. Merton looks similar to Daniel. Kat's father has given her the nickname 'Kitty Kat' and suffers an accident in the garage.

Book and TV episode The Merton's pet Cocker Spaniel. Despite being named Killer, he is actually a very timid dog. Killer goes missing during the book's events but returns at the end of the story.
Daniel Merton

Book and TV episode Daniel is Kat's immature and prank-pulling little brother. He fights with his sister over possession of the sponge creature, which through some research, Daniel discovers is actually a monster known as the Grool.

Book and TV episode Carlo is Daniel's best friend. The two spend frequent time together and most of that time is spent annoying Kat. The discovery of the Grool sparks Carlo's curiosity, but upon trying to study it, a nail goes through his foot.
The Grool

Book and TV episode A sponge-like creature said to bring bad luck to whoever discovers it. Kat and Daniel attempt to destroy the creature many times to no avail. The Grool is finally destroyed when Kat softly sings to it as acts of kindness repulse the creature.
Mrs. Vanderhoff

Book and TV episode An intelligent but strict teacher of Kat's. Hoping she'll know something, Kat gives the Grool to Mrs. Vanderhoff. As she tries to investigate, Mrs. Vanderhoff accidentally slams her fingers in the drawer.
Mrs. Twitchell

Book Mrs. Twitchell is the school nurse. She treats Mrs. Vanderhoff's injury.
Aunt Louise

Book The slightly eccentric aunt of Kat and Daniel. She knows a lot about astrology and tarot cards. Kat hopes she'll know what to do about the Grool, but the creature pretends to be a normal sponge, leading Aunt Louise to think Kat was playing a joke on her.
Dave and Unnamed Boy

Book Two neighborhood bullies that steal and play catch with the Grool. Dave gives it back to Kat when his friend gets injured.

TV episode In the episode, Kat leaves the Grool with Mrs. Vanderhoff overnight. Fearing it could do more damage, she, Daniel, and Carlo sneak into the school, where a janitor is cleaning up. He ends up collapsing thanks to the Grool's magic.
The Lanx

Book and TV episode The Lanx is the Grool's deadlier cousin, said to resemble a potato with razor-sharp teeth. Daniel discovers its existence when researching the Grool in the Encyclopedia of the Weird. At the end of the book, the returned Killer finds the Lanx beneath the kitchen sink.
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