Mẫu Thoải, or Thủy cung Thánh Mẫu (水宮聖母) is a goddess in Vietnamese non-Buddhist traditional religion. The goddess features in Chầu văn religious ceremonies and music. She presides over the heavenly water palace Thoải Phủ, one of the Four Palaces (Tứ Phủ) where the "spirits of the Four Palaces" (thánh Tứ Phủ) correspond to the elements.