A Guard Worm is a large, violent worm, that guards various places in Bikini Bottom. They are a parody of guard dogs. This one was first seen in the episode The Lost Mattress, where it was living in the dump, at the moment on Mr. Krabs' misplaced money filled matrress, where Squidward was violently mauled by it various times. Another one was seen in the episode BlackJack when SpongeBob's cousin BlackJack had one guarding his front entrance. In Best Frenemies one was guarding the KelpShake store, on the night Krabs and Plankton tried to steal the KelpShake's formula. There are various Worms that work for the Bikini Bottom Police Force. In the episode Slide Whistle Stooges, three guard worms were supporting the police to go against Squidward, but then attacked on police officer when he called insulted them after they were going wild by the terrible whistle sound Squidward made. They are Green and have Silver spiked collars.
- Slide Whistle Stooges
- The Lost Mattress
- Toy Store of Doom
- Best Frenemies
- Plankton's Pet
- SpongeBob SquarePants featuring Nicktoons: Globs of Doom (second Bikini Bottom level)
- The Guard Worm is a spoof on the guard dog.
- Their spiked collar represent the ones that dangerous dogs normally wear.
- In the episode BlackJack, the guard worm's eye's are red, unlike every other appearance of guard worms.
- The Guard Worm in "Toy Store of Doom" was not mean, or violent, unlike Worms from all other episodes.