The Deinonychosauria were a successful clade of theropods in the Cretaceous period. These carnivores are known for their switchblade-like second toes. The clade has been divided into two further clades — Dromaeosauridae and Troodontidae.

Dromaeosauridae includes some of the most fearsome killers of the Cretaceous period: Deinonychus, Velociraptor, and Utahraptor. The largest known of these is possibly Utahraptor, and the controversial Microraptor was among the smallest (40 cm or 16 in?).

Troodontids date from the late Cretaceous, and were lighter and slimmer than the dromaeosaurids. Some of these were Troodon and Saurornithoides.

By some definitions, Deinonychosauria and Dromaeosauridae are synonyms.