The Gray Catbird (Dumetella carolinensis), also spelled Grey Catbird, is a medium-sized northern American perching bird of the mimid family. It is the only member of the "catbird" genus Dumetella. Like the Black Catbird (Melanoptila glabrirostris), it is among the basal lineages of the Mimidae, probably a closer relative of the Caribbean thrasher and trembler assemblage than of the mockingbirds and Toxostoma thrashers. In some areas it is known as the Slate-colored Mockingbird.

Adults weigh around 35–40 g (1.2–1.4 oz) and are plain lead gray almost all over. The top of the head is darker. The undertail coverts are rust-colored and the remiges and rectrices are black, some with white borders. The slim bill, the eyes, and the legs and feet are also blackish. Males and females cannot be distinguished by their looks; different behaviours in the breeding season is usually the only clue to the observer. Juveniles are even plainer in coloration, with buffy undertail coverts.

This species is named for its cat-like call. Like many members of the Mimidae (most famously mockingbirds), it also mimics the songs of other birds, as well as those of Hylidae (tree frogs), and even mechanical sounds. Because of its well-developed songbird syrinx, it is able to make two sounds at the same time. The alarm call resembles the quiet calls of a male mallard.