A backlight unit includes a plurality of light sources emitting light in a first direction with a predetermined orientation angle and a plurality of light guide panels, each including a light incident section and a light emitting section. The light incident section has a first surface to receive light emitted from one or more of the light sources in the first direction, and the light emitting section is to emit light received from the light incident section in a second direction. Also included is a reflecting member adjacent the light guide panels. The light emitting section of each light guide panel includes a portion that decreases in thickness from a first point to a second point, wherein the first point is closer to the light incident section and the second point.