The Thickskull Tribe is a prehistoric tribe on Planet Granite. One of two tribes seen on the planet (along with the Meek Tribe), the Thickskulls are overweight bruisers who enjoy bullying their neighbours. They wear very little clothing, covering their modesty with a patterned, yellow cloth. Their leader wears a simple necklace.
One day, the Thickskulls invaded Meek territory and attacked the natives, pulling back their tentacles. Visitors Amy Rose and Tekno the Canary jumped into help, but Tekno was quickly captured by one of the Thickskulls. Amy chased them all off with her crossbow, the leader scared by her "powerful magic". Unfazed, the Thickskulls returned to conquer once more but arrived to find the Meeks laughing at them. The leader was saddened to hear that it was "old hat to fight", having been looking forward to "bashing [their] brains in". Instead, representatives from both tribes sat down over a plate of cucumber sandwiches and discussed the cause of the Thickskulls' anger.
- They resemble Earl from ToeJam and Earl, possibly their basis.