| Named By: | Lawrence Lambe in 1913 |
| Time Period: | Late Cretaceous, 75.5-75 Ma |
| Location: | Canada, Alberta - Dinosaur Park Formation |
| Size: | Around 5.5 meters long, but some specimens show that it could have grown slightly larger |
| Diet: | Herbivore |
| Fossil(s): | Many remains, some of almost complete skeleton, and bone beds are many individuals that died together |
| Classification: | | Chordata | Reptilia | Dinosauria | Ornithischia | Cerapoda | Ceratopsia | Ceratopsidae | Centrosaurinae | |
| Also known as: | | Styracosaurus parksi | Styracosaurus sphenocerus | Styracosaurus borealis | |
Styracosaurus ( sti-RAK-a-SOR-as; meaning "spiked lizard" from the Ancient Greek styrax/sturax "spike at the butt-end of a spear-shaft" and sauros/sauros "lizard") was a genus of herbivorous ceratopsian dinosaur from the Cretaceous Period (Campanian stage), about 75.5 to 75 million years ago. It had four to six long horns extending from its neck frill, a smaller horn on each of its cheeks, and a single horn protruding from its nose, which may have been up to 60 centimetres (2 ft) long and 15 centimetres (6 in) wide. The function or functions of the horns and frills have been debated for many years.
Styracosaurus was a relatively large dinosaur, reaching lengths of 5.5 metres (18 ft) and weighing nearly 3 tonnes. It stood about 1.8 meters (6 ft) tall. Styracosaurus possessed four short legs and a bulky body. Its tail was rather short. The skull had a beak and shearing cheek teeth arranged in continuous dental batteries, suggesting that the animal sliced up plants. Like other ceratopsians, this dinosaur may have been a herd animal, traveling in large groups, as suggested by bonebeds.
Named by Lawrence Lambe in 1913, Styracosaurus is a member of the Centrosaurinae. One species, S. albertensis, is currently assigned to Styracosaurus. Other species once assigned to the genus have since been reassigned elsewhere.