The Grim Adventures of Billy and Mandy Wiki
The Grim Adventures of Billy and Mandy Wiki
Big Trouble in Billy's Basement
Series Grim & Evil
Season 1
Production code 112
Writer Gord Zajac
Broadcast information
Broadcast number 12A
Cartoon Network US Premiere October 11, 2002
Paired with Tickle Me Mandy and Christmas Con Carne
Chronological information
Billy & the Bully
Christmas Con Carne

Big Trouble in Billy's Basement is the first segment of the twelfth Grim & Evil episode.


Despite repeated warnings from Grim, Billy can't resist the temptations of The Bad Book. Upon reading it, he is brainwashed and possessed by the fearsome deity Yog-Sothoth, who wishes to enter the world and recreate it in his own image. In order to achieve this, both the book and Grim's scythe are needed. With the gift of Yog-Sothoth's evil powers, Billy easily overpowers Grim and takes the scythe. He sets up shop in the basement of his family home, where after studying the unholy text, he finds the right incantation. Using the scythe, he rips a hole in the fabric of space and time, allowing horrible monsters and magic to wreak havoc and stain the rug.

In the meantime, Grim and Mandy call on Hoss Delgado for help. After some friendly fire, Hoss quickly identifies the goings-on as Yog-Sothoth's work. They find the possessed Billy in the basement with Yog-Sothoth, who is about to breach the gate. When the combined forces of Hoss and Grim fails to vanquish him, Mandy shoves Billy into the portal with the book and the demon back to The Dreamlands along with him. However, not wanting lowly humans among them, the Outer Gods send Billy back home to his friends' scorn and pity.


  • Story by: Gord Zajac
  • Storyboard by: Chris McCulloch
  • Directed by: Robert Alvarez, John McIntyre


  • This is the second appearance of Hoss Delgado.
  • The title "Big Trouble in Billy's Basement" is a parody of the movie title "Big Trouble in Little China".


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Billy & The Bully
Grim & Evil Episodes Next:
Christmas Con Carne