Physignathus is a genus of large, diurnal and arboreal agamid lizards, commonly known as Water dragons. There are two species, the Chinese water dragon Physignathus cocincinus, and the Australian water dragon Physignathus lesueurii. They are sometimes kept as pets, especially P. cocincinus.

Physignathus cocincinus (Cuvier, 1829)is found throughout South-East Asia, in Thailand, Cambodia, Vietnam and south China. These lizards are semi-aquatic, using their laterally-compressed tails to propel them when swimming. They are able to remain submerged for long periods of time. Like many lizards, water dragons have a parietal eye, a light-sensitive "third eye" located in the top of the head.

Physignathus lesueurii (Gray, 1831)males are easily distinguished from the females as they have a red coloured chest and belly, which is mostly visible when they lift their heads in defensive mode. This species occurs in the eastern states of Australia, and is locally designated as the Eastern Water Dragon.[1] The species are usually shy creatures in the wild, that may only make themselves known to the passer-by from the sound of them dropping into a waterway. However, in breeding season, the mothers may become more aggressive to distract any potential predators from capturing her young. Juveniles are very sociable, playful creatures and are usually found in groups ranging from 3 - 8 young dragons.