The image sensor and an image sensing system including the same are provided. The image sensor includes a semiconductor substrate, a pixel array formed at a pixel area located in the semiconductor substrate and comprising a plurality of photoelectric converts, a plurality of driver circuits formed at a circuit area defined in the semiconductor substrate. The image sensor includes at least one heat blocker or heat shield. The at least one heat blocker may be formed between the pixel area and the circuit area in the semiconductor substrate. The heat blocker or heat shield may block or dissipate heat generated at the circuit area from being transferred to the pixel area through the semiconductor substrate. The heat blocker or heat shield may be used in image sensors using a back-side illumination sensor (BIS) structure or image sensors using a silicon on insulator (SOI) semiconductor substrate.