A semiconductor package includes a first structure including a first semiconductor chip, and a second structure on the first structure. The second structure includes a second semiconductor chip, a semiconductor pattern horizontally spaced apart from the second semiconductor chip and on a side surface of the second semiconductor chip, an insulating gap fill pattern between the second semiconductor chip and the semiconductor pattern, and through-electrode structures. At least one of the through-electrode structures penetrates through at least a portion of the second semiconductor chip or penetrates through the semiconductor pattern.