Callobius claustrarius is a species of spider in the family Amaurobiidae.

Head and legs are reddish brown, the abdomen is dark grey with an extended brown surface, dotted with lighter brown specks.

Adults can be found from autumn to spring.

In Europe, it is found in mountainous regions, especially in old, moist forests under rocks.

The subspecies C. claustrarius balcanicus (Drensky, 1940) is only found in Bulgaria.