Gastonia is a genus of herbivorous ankylosaurian dinosaur from the Early Cretaceous of North America, around 139 to 125.77 million years ago. It is often considered a nodosaurid closely related to Polacanthus. Gastonia has a sacral shield and large shoulder spikes.

The type specimen of Gastonia burgei (CEUM 1307) was discovered in a bonebed from the limestone strata of the lower Cedar Mountain Formation in Yellow Cat Quarry, Grand County, eastern Utah, the type specimen consisting of a single skull. The type specimen was found alongside 4 partial skeletons of Gastonia that were placed as paratypes, along with the type specimen of Utahraptor and an iguanodontid. Gastonia is among the most common dinosaur fossils in the Cedar Mountain Formation, with many individuals being found across several quarries in the southwest. In 2004, the number of skulls was reported as four, in 2014 this had risen to ten. Gastonia was formally named and described by James Kirkland in 1998, from the holotype specimen and other fossil material recovered beginning in 1989. The name Gastonia honors US paleo artist and CEO of Gaston Design Inc. Robert Gaston. The species G. burgei was named for the director of the College of Eastern Utah Prehistoric Museum, Donald L. Burge.

Gastonia burgei, was found in rocks of the Cedar Mountain Formation's Yellow Cat Member, which has been dated to the Valanginian, 139 to 134.6 million years ago.

A second species, G. lorriemcwhinneyae, was described from the same formation in 2016 based on a large bonebed that had been found by Lorrie McWhinney in 1999, probably formed when a group died of drought or drowning. The incomplete type specimen (skull roof) and its paratypes based on many other portions of the skeleton were collected by the Denver Museum of Nature and Science from Lorrie's Site in Grand County, Utah. Although the type locality of this species was originally reported as the lower Ruby Ranch Member, it was later corrected to be the older Poison Strip Member (Hauterivian-Barremian).

All together, more complete material exists for Gastonia than for any other basal ankylosaur. A wealth of disarticulated material from a bonebed presents problems as it can be hard to tell how many spikes a particular Gastonia actually had.

In the late twentieth century a skeleton was mounted made of polyurethane casts of skeletal elements of various individuals. Distortions in the fossils were corrected and missing elements completed. This made Gastonia the first basal ankylosaurian dinosaur to have been mounted for display at the Denver Museum of Nature and Science, together with the related Gargoyleosaurus.

Gastonia was a medium-sized ankylosaur. In 1998, Kirkland estimated its length at 6 m (20 ft). In 2010, Gregory S. Paul indicated a body length of 5 m (16 ft) and a weight of 1.9 t (4,200 lb). The skeleton mount has a length of 4.59 m (15.1 ft) with a hip height of 1.12 m (3.7 ft).

It is difficult to determine distinguishing traits of Gastonia because its affinities are uncertain. However, in 1998 Kirkland established three characters which were unique for the Ankylosauria as a whole and thus likely autapomorphies, unique derived traits. On the midline of the front snout, the bony core of the upper horny beak, a broad, gradually curved, notch is present between the snout bones, the praemaxillae. The bony nostrils are placed far to the rear. At the underside of the braincase, the basisphenoid, the basipterygoid processes are longitudinally stretched.