A window panel includes a plurality of unit patterns arranged along a first direction, each of the plurality of unit patterns having a base surface portion, a plurality of inclined portions, the plurality of inclined portions being inclined upwardly from the base surface portion, and a top portion disposed at a top of the inclined portions, wherein a lower edge of a first inclined portion of each unit pattern of the plurality of unit patterns adjoins a lower edge of a second inclined portion of a neighboring unit pattern.