| Named By: | Louis Agassiz in 1835/39/43 |
| Time Period: | Late Devonian-Mississippian~383-318 Ma |
| Location: | Possibly worldwide with some known locations including Belgium, Russia and the United Kingdom |
| Size: | About 50 centimetres long, some variation between species |
| Diet: | Carnivore/Piscivore |
| Fossil(s): | Many individuals |
| Classification: | | Chordata | Sarcopterygii | Porolepiformes | Holoptychiidae | |
Holoptychius is an extinct genus of porolepiform lobe-finned fish from the Middle Devonian to Carboniferous (Mississippian) periods. It is known from fossils worldwide. The genus was first described by Louis Agassiz in 1839.