|Release date:||October 31, 2003|
|Running time:||22 minutes|
While out trick-or-treating, Grim tells Billy and Mandy the story of a power-hungry practical jokester named Jack O'Lantern. Grim tells how Jack managed to escape death, but at the cost of losing his head.
Dressed as the Grim Reaper and armed with Grim's real scythe, Billy stumbles upon Jack O'Lantern's doorstep on Halloween Night. Jack manages to steal Grim's scythe, hoping to use its power to seek his revenge on the people of Endsville, and make it so that the sun would never rise again, and that it would be Halloween every night forever. Jack kidnaps Grim to cut off his head out of revenge for Grim decapitating him years ago. But before he can, Billy pops up and distracts him by pulling up his robe and shaking his rump (revealing that he was wearing nothing under his robe) at him, which Grim liked. Then, with the help of Mandy and Irwin, the gang manages to save Grim and banish Jack to the Underworld where he was beaten up by many humorless demons for pulling a prank on them.