Gonocephalus grandis more commonly known as the Giant Anglehead Lizard, is one of many lizards found in the evergreen forests of Malaysia. The species is distributed from Southern Thailand, Laos, Peninsular Malaysia and Sumatra to Borneo.

The Giant Anglehead Lizard is classified under the family Agamidae. It has the general characteristics of a robust body; the male has a nuchal and dorsal crest which are separated, whilst the female lacks a dorsal crest. Typically, the Giant Anglehead Lizard is greenish-brown on its dorsum, appearing darker in colour when under stress. The flanks of the female lizard are brownish-green to nearly black while the male is easily distinguished by its blue flanks with yellow spots. The lizard is able to grow up to 160 mm in length.

The Giant Anglehead Lizard inhabits primary forests at elevations of up to 1,400 m above sea level. One can easily find this lizard near streams or small rivers, camouflaged on the tree trunks. At night the lizards rest on leaves of saplings or twigs overhanging the water bodies.

The diet of this lizard largely consists of caterpillars, ants, flies and cockroaches. The lizard lays up to six eggs at a time. The incubation period of the eggs is between 69 to 75 days. The conservation status of the Giant Anglehead Lizard is least concerned but the species is protected under the Malaysian Wildlife Act 2010.