Wannanosaurus (wah-NAN-oh-SAWR-us) ("Wannano lizard", named after the Province in China, where it was discovered) was a primitive pachycephalosaurian dinosaur from the Late Cretaceous Period of China, about 80 million years ago.

It was a bipedal homalocephalid (like Homalocephale), sharing the characteristic of a flat-topped, thickened skull. It may have been a herbivore, grazing on low lying plants and living in a herd. It was a tiny dinosaur about 2 feet (60 cm) long. It probably engaged in head-butting activities. It was an herbivore that walked on two strong legs, had short arms, a stiff tail, and a thick-set body.

It was active during the Campanian age.