The giant thicket rat (Grammomys gigas) is a species of rodent in the family Muridae which is restricted to a small area of Kenya.

[4] The giant thicket rat is an arboreal species which is found in montane moist forest and high-elevation scrub.

[2] The giant thicket rat is losing habitat due to the clearance of forest for timber, firewood and conversion to agricultural land.

Much of the giant thicket rat's range lies within Mount Kenya National Park but it is a priority to establish other protected areas for this species.

The giant thicket rat is classified as endangered because its range is less than 2,000 km2 (770 sq mi) and is in a single locality where the habitat is being degraded.