The black giant squirrel or Malayan giant squirrel (Ratufa bicolor) is a large tree squirrel in the genus Ratufa native to the Indomalayan zootope. It is found in forests from northern Bangladesh, northeast India, eastern Nepal, Bhutan, southern China, Myanmar, Laos, Thailand, Malaysia, Cambodia, Vietnam, and western Indonesia.
Head and body length varies from 35 to 58 centimetres in length, and the tail is up to 60 centimetres long, with an overall length of up to 118 centimetres. The back, ears and bushy tail are deep brown to black with a lighter buff-colored belly.
R. bicolor is diurnal and arboreal, but sometimes climbs down from the forest canopy to feed on the ground. The black giant squirrel rarely enters plantations or settlements, preferring the wild forest.
Its diet consists of seeds, pine cones, fruits, and leaves. It is primarily solitary, and has a litter of from 1 to 2 young, which it raises in a drey (or nest), often located within a hollow space of a tree.