Xixiasaurus, a troodontid dinosaur, lived during the Late Cretaceous Period in what is now China. The sole known specimen was unearthed in Xixia County, Henan Province, central China, and was officially designated as the holotype of the new genus and species Xixiasaurus henanensis in 2010. The names of the dinosaur refer to the areas of its discovery and can be translated as "Henan Xixia lizard." The specimen comprises an almost complete skull (except for the hindmost part), a section of the lower jaw with teeth, and a partial right forelimb.

Estimates suggest that Xixiasaurus measured about 1.5 meters (5 ft) in length and weighed around 8 kilograms (18 lb). As a troodontid, it possessed bird-like characteristics, featuring a light and agile build, grasping hands, and a prominent, sickle-shaped claw on the second toe. Its skull was elongated, with a long, slender snout that formed a tapering U-shape when viewed from below.

The frontal bone of the forehead displayed a dome-like structure in side view, indicating an enlarged braincase. Xixiasaurus differed from other troodontids in that the front portion of its lower jaw (dentary bone) was downturned. Notably, its teeth lacked serrations, and instead, the carinae (front and back edges) were smooth and razor-sharp. Another distinguishing feature was the presence of 22 teeth in each maxilla, setting it apart from other troodontid genera where the maxillary tooth count varied either higher or lower.