Dufrenoyia is an extinct genus of Cretaceous ammonites included in the family Parahoplitidae. These fast-moving nektonic carnivores lived in the Cretaceous period (Aptian age). The type species of the genus is Ammonites dufrenoyi.
Fossils of species within this genus have been found in the Cretaceous sediments of Germany, Mexico, Morocco, Spain, the United Kingdom, United States, Colombia and Venezuela.