A backlight unit for a liquid crystal display panel includes a lamp, a plurality of optical sheets, a light guide that guides light from the lamp toward the optical sheets, and a reflector facing a rear surface of the light guide. The light guide includes a first plurality of geometric shapes at the rear surface thereof that substantially directs the light incident on the light guide toward the optical sheets, and a second plurality of geometric shapes at a peripheral portion of the rear surface thereof to prevent the reflector from sticking to the light guide, a density of the second plurality of geometric shapes is less than the density of the first plurality of geometric shapes.