Holcodiscus is an extinct ammonite genus placed in the family Holcodiscidae.

Species in this genus were fast-moving nektonic carnivores.

[2] The type species of the genus is Ammonites caillaudianus.

[2] Circular to rectangular whorl section; fine, low, straight or flexuous simple or branched ribs, periodically truncated by thin, high, enlarged ribs bearing lateral and ventrolateral tubercles; inner whorls tending to have depressed whorl section and to resemble Olcostephanus.

[3] Source:[2] Fossils of species within this genus have been found in the Cretaceous sediments of Austria, Bulgaria, Chile, Colombia, Czech Republic, Slovakia, France, Italy, Morocco, Spain and Russia.