Demodex is a genus of tiny parasitic mites that live in or near hair follicles of mammals.

Around 65 species of Demodex are known. Two species living on humans have been identified: Demodex folliculorum and Demodex brevis, both frequently referred to as eyelash mites. Different species of animals host different species of Demodex. Demodex canis lives on the domestic dog. Infestation with Demodex is common and usually does not cause any symptoms, although occasionally some skin diseases can be caused by the mites. Demodex is derived from Greek dēmos fat + dēx, a wood worm.