Family : Agamidae 
Species : Gonocephalus grandis 
Size (snout to vent) : males 16 cm, females 14 cm
Size (total length) : males to 60 cm, females to 52 cm.

Stunning in appearance, the Great Anglehead Lizard occurs along forest streams in lowland and hill rainforest and particularly freshwater swamp forest. 
 

This species leads an arboreal lifestyle, and can be found clinging to streamside vegetation and nearby tree trunks. Grismer (2011) reports that males may lurk up to 15 metres above ground, whilst females and juveniles tend to live much closer to ground level, sometimes resting on boulders. 

When disturbed these lizards may leap into the water and quickly swim away, sometimes submerging themselves and clinging to the stream bed to evade a potential threat.

In common with most other agamids, they prey on a variety of invertebrates including various insects, insect grubs and some spiders.

Males of this species possess well-developed head and body crests, and are a striking bright green in colour with blue flanks adorned with pale yellow spots. Females and juveniles are less brightly coloured, but are patterned with stripes and other markings of various shades of brown.

The Great Anglehead Lizard occurs in southern Thailand, Peninsular Malaysia (including larger islands such as Penang and Tioman), Sumatra (including the Mentawai Islands) and Borneo. A separate population is also reported from southern Laos and Vietnam. The species is absent from Singapore.