Glebocarcinus oregonensis, commonly known as the pygmy rock crab, is a species of crab found on the Pacific coast of North America.

It is usually red/brown but this may vary; their legs have many setae (hairs). The carapace reaches a width of about 5 centimetres (2 in), and is widest at the 7th or 8th lateral tooth.^[2] The chelipeds are black at the tip, and the dactylus of the cheliped has no spiny ridges; the dorsal surface is covered with small tubercles (rounded projections), and males have larger chelipeds than females.^[3]

Glebocarcinus oregonensis is found mostly in crevices, holes (dead barnacles) and under rocks.^[3] They can live in depths of up to 1,400 feet (430 m).^[2] They are nocturnal feeders, feeding mostly on small barnacles, snails, bivalves, worms, green algae and Pacific oysters.^[3] Predators include Pacific cod, river otters and red rock crab.^[3]

Breeding occurs during the summer, and the Puget Sound females carry eggs from November to May.^[3] It is not unusual to find harems consisting of one male with as many as seven females.^[3] Males may carry females that are molting and continue until their new shell hardens, for mating occurs after females molt.^[3]