The Kali Gandaki or Gandaki River (also known as the Narayani in southern Nepal and the Gandak in India) is one of the major rivers of Nepal and a left bank tributary of the Ganges in India. It is also called Krishna Gandaki in Nepal. In Nepal the river is notable for its deep gorge through the Himalayas and its enormous hydroelectric potential. It has a total catchment area of 46,300 square kilometers (17,900 sq mi), most of it in Nepal. The basin also contains 3 of the world's 14 highest mountains over 8,000m, the three being Dhaulagiri I, Manaslu and Annapurna I. Dhaulagiri I is the highest point of the Gandaki basin. It lies between the similar Kosi system to the east and the Karnali (Ghaghara) system to the west.

The river is called Sapta (seven) Gandaki for seven tributaries rising in the Himalaya or further north along the main Ganges-Brahmaputra divide. These are called Daraudi, Seti, Madi, Kali, Marsyandi, Budhi, and Trisuli.

The Kali Gandaki river source is at the border with Tibet at an altitude of 6,268 m (20,564 ft) at the Nhubine Himal Glacier in the Mustang region of Nepal.