Map showing the Ghaghara and Gandaki tributaries of the Ganges.

Ghaghara (also called the Gogra or the Karnali in Tibet and upper Nepal) is a river in Nepal and northern India, one of the largest affluents of the Ganges. It rises in the southern slopes of the Himalayas in Tibet, at an altitude of about 13,000 feet (3962 metres) above sea level. The river flows south through Nepal as the Karnali River. In Uttar Pradesh state the Ghaghara flows in a southeast direction to the town of Chapra, where, after a course of 570 miles (917 kilometres), it joins the Ganges. The river is one of the most important commercial waterways of Uttar Pradesh.

Deforestation in the upper reaches has significantly increased the sediment load on the Ghaghara (and the downstream Ganges). The Gangetic dolphin or susu, frequently sighted on the Ghaghara in earlier times, is rare today, possibly due to difficulties in navigating shallow waters. The Ghaghara is the furthest upstream in the dolphin range.

Important towns on the river include Faizabad-Ayodhya, Dohrighat, and Tanda.

The river (but more likely, a tributary) may be the famed Ramayana river Sarayu.