Tokay Gecko (Gekko gecko 大壁虎 / 蛤蚧 )
The Tokay Gecko is a nocturnal gecko, and their native habitat is rainforest trees and cliffs, but they have adapted to human habitations, and can be often seen on walls and ceilings at night in search of insect prey. They are quite common on Ma On Shan peak, and also along Bowen Road in a more urban setting.
The local population probably has been bolstered by escapees from snake/medicine shops. They are aggressive carnivores and eat insects, lizards and even small mammals and birds. They can get quite big up to 30-40 cm for males. They can differ in colour, either grey or bluish, as per the pictures below - which I have been told are of the non-native variety, but running wild on the peak.
They have a distinctive call of "tokaaaaay" from which the name comes.