Harpoceras is an extinct genus of ammonite belonging to the family Hildoceratidae.

[2] Shells of Harpoceras species show strong dimorphism in their size.

Some species have midlateral groove, or series of undulating depressions on inner half of whorl.

[1][2] Fossils of species within this genus have been found in the Lower Jurassic rocks of Europe, Northern Africa, Russia, Japan, Borneo, New Zealand, Indonesia, North and South America (Argentina; El Cholo and Los Molles Formations).

[1] Two species, Harpoceras serpentinum and Harpoceras falciferum, are index fossils used for stratigraphic correlation and dating of rocks of the Toarcian stage of the Lower Jurassic.