The southern silvery kingfisher (Ceyx argentatus) is a species of bird in the family Alcedinidae that is endemic to the Philippines. Its natural habitats are subtropical or tropical moist lowland forests and rivers. It is threatened by habitat loss. In the Philippines, it is called kasay-kasay, and figures in the legend concerning the discovery of the Catholic image of Our Lady of Caysasay. This species and the northern silvery kingfisher were formerly considered conspecific and called the silvery kingfisher.