An exemplary embodiment provides a backlight unit including: a bottom chassis; a supporter positioned to extend along one edge of the bottom chassis; a light source unit fixed to the supporter; and a light guide plate that is positioned on the bottom chassis and is configured to transmit light emitted from a light source of the light source unit. The supporter may include a main body of which at least one corner area is cut and an insertion portion that is positioned at the corner area. Each of the main body and the insertion portion may include a base portion and a side wall, and the side wall of the insertion portion may extend from the side wall of the main body and in a direction different than a direction of the side wall of the main body.