Nagas are serpent beings from ancient Indian mythology. In early Hindu art, Nagas have human upper torsos but are snakes from the waist down. In Buddhist iconography, nagas sometimes are giant cobras, and sometimes they are more like dragons, but without legs. In some parts of Asia, dragons are considered to be a type of naga.
In Buddhist sutras and myths, nagas usually are wise and beneficent. In Mahayana Buddhism, nagas often are depicted as water deities who guard the sutras in their palaces.
For example, it is said the Wisdom Sutras were given to the nagas by the Buddha, who said the world wasn't ready for their teachings. Centuries later they befriended the philosopher Nagarjuna and gave the sutras to him.