A mask, a mask assembly, and a method of fabricating a mask are disclosed herein. The mask comprises a polymer film in which at least one cell region and at least one peripheral region are defined, the at least one peripheral region surrounding the at least one cell region, a conductive layer disposed on the polymer film and including a metal, an inorganic layer disposed between the polymer film and the conductive layer and including a silicon-based inorganic material, and holes that penetrate the polymer film, the conductive layer, and the inorganic layer and overlap the at least one cell region in a plan view.