Gigantspinosaurus, meaning “giant spined lizard”, is a genus of stegosaur dinosaur from the Late Jurassic Period. It was found in the Upper Shaximiao Formation of Zigong, Sichuan, China. It is known from a partial skeleton missing most of the skull, hind feet, and tail. The type species, G. sichuanensis, was described in 1992. It was known as Nomen nudum until 2006.
This dinosaur had a unique appearance. It had small dorsal plates and large shoulder spikes (or spines). The spines were twice as long as the shoulder blades. It was about 13 feet long.