A foldable display device includes: a foldable display layer, and a backing film coupled to the display layer. The backing film has a stiffness in a first direction parallel to a bending axis of a plane of the display layer that is at least ten times higher than a stiffness of the backing film in a second direction perpendicular to the bending axis in the plane of the display layer. The backing film includes a plurality of metal fibers arranged parallel to each other in the first direction and a film that mechanically couples the plurality of metal fibers to each other and that mechanically couples the plurality of metal fibers to the display layer, where the film includes material that has a modulus of elasticity that is less than 3% of a modulus of elasticity of a material of the plurality of metal fibers.