|Series||The Grim Adventures of Billy and Mandy|
|Voiced by||Maxwell Atoms|
Jeffrey "Jeff" the spider is an extremely generous spider who supposedly is the son of Billy, since Billy is the one who hatched him from his egg. Since Billy hates bugs, especially spiders, he repeatedly tries to kill him, despite his kindness. His best friend is Fred Fredburger and both of them now work for a superhero team called Underfist along with Hoss.
FusionFallEditIn FusionFall he appeared for the first time in the birthday bash event, and his model doesn't move, like Zon's and Ship's. You can also get a Jeff Helmet, and his eggs as thrown weapons. He later appears at Habitat Homes during the mother's day event looking for the Blowfish egg after Billy kicked it, though now he is gone.
Like Zon and Ship, Jeff received animation when added once more after the Birthday Bash.
- Jeff has only appeared for the Birthday Bash and Mother's Day events. He was removed after both events were concluded.
- In Underfist: Halloween Bash, it is revealed that the movie's main vilain, Bun-Bun, is the one who caused Billy's fear of bugs, and Jeff.