Crabs are crustaceans from Planet Earth and Mobius often found in the ocean or on beaches. They are well known for their two pincers and having to walk sideways on their spindly legs.
- Crabmeat is a famous Badnik from the Green Hill Zone that heavily resembles a crab. It has two overly large pincers that can also fire energy blasts (although hasn't done so in Sonic the Comic. Parts of Crabmeat also appear in several of The Seven Badniks. Shellcracker is another crab Badnik, based on a fiddler crab, although it only appeared in Sonic the Comic Online. Hermit crab badniks, Spikes and later Turbo Spiker, were also used.
- Poison crabs exist in the Monster World, but Shion decided to run past them rather than fight them.
- Crab Sea Nesbitt is a resident of Trituna who travelled to the Beanson Coast Zone to fight Sonic the Hedgehog. After his attempt failed, he withdrew to the ocean to fight Sonic there, but soon realised the error of his ways when Zone Leader Sharka Khan was ousted.
- Captain Claw was previously a crab that used to terrorise the Mobian Channel until he was defeated by Knuckles the Echidna. However, it was hinted that he was let go due to there being nowhere to lock him up with Doctor Robotnik in charge.
- Real Earth crabs were sighted in Ecco the Dolphin's first adventure.