Compsemys is an extinct genus of prehistoric turtles from the Late Cretaceous and Paleocene of North America and possibly Europe.

The type species C. victa, first described by Joseph Leidy from the Hell Creek Formation in Montana in 1856,[1] and another probable species C. russelli (originally placed in the separate genus Berruchelus), described in 2012, from Paleocene deposits in France.

Its affinites have long been uncertain,[1] but it has recently been considered to be the most basal member of Paracryptodira, despite the clade first appearing in the Late Jurassic, and is sometimes included in its own family, Compsemydidae.

[5] The skull resembles that of the alligator turtle, with a sharply hooked beak; Compsemys must have been an aquatic carnivore.

[5] The oldest known shell fragments identifiable as Compsemys are known from the Santonian stage of the Late Cretaceous in North America, while European remains are not known until the Paleocene.