The following is a list of characters from How to Kill a Monster in the order they are mentioned or appear.

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


Character Medium Description
Gretchen Allen

Book and TV episode The main protagonist and narrator. She is tall and thin, and has long, straight, blonde hair.
Gretchen and Clark's parents

Book and TV episode Gretchen's parents divorced when she was two. Clark's parents are also divorced. Gretchen's real mother and Clark's real father are not named. However, Gretchen's father married Clark's mother, making the two kids step-siblings.
Grandma Rose

Book and TV episode Grandma Rose is Gretchen's grandmother. Grandma Rose loves to cook, and she is a really kind person. She lives with her husband in a old castle-like mansion located in the middle of a swamp. Along with Grandpa Eddie, she is described by the kids as being strange and smelly.
Grandpa Eddie

Book and TV episode Grandpa Eddie is Gretchen's grandfather. Grandpa Eddie is very hard-of-hearing, and he misunderstands some words that people say. He and his wife say that they love their grandchildren. However, in the book, they abandon them with a killer swamp monster.
Clark Allen

Book and TV episode Clark is Gretchen's stepbrother. He has curly brown hair and wears glasses. He loves to read comic books, especially scary ones. Clark can be very stubborn and gets scared easily, which makes him an easy target to Gretchen's jokes.

Book Charley is Gretchen and Clark's dog. It accompanies them on the trip and protects them from the Swamp Monster's attack.

Book Arnold is Clark's best friend. Gretchen describes him in the book as being "the biggest nerd in the neighborhood". He is only mentioned.
Swamp monsters

Including the main Swamp Monster

Book and TV episode They're species of swamp creatures covered in green fur, which are able to talk. They have huge gorilla bodies and alligator faces. The first monster to appear in the book is allergic to humans, but it's unknown if the other swamp monsters also are.
General store worker

Book This man brings a pink envelope to Grandpa Eddie and Grandma Rose's home from the general store.
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