| Named By: | Louis Agassiz in 1845 |
| Time Period: | Late Silurian-Early Devonian |
| Location: | Europe. North America |
| Size: | 7.5 centimetres long |
| Diet: | Carnivore/Piscivore |
| Fossil(s): | Many known specimens |
| Classification: | | Chordata | Acanthodii | Climatiiformes | Climatiidae | |
| Also known as: | | Ctenacanthus latispinosus | Euthacanthus gracilis | Euthacanthus grandis | Euthacanthus macnicoli | Euthacanthus macnicolli | |
Climatius (meaning inclined fish or tilted fish) is an extinct genus of spiny shark. Fossils have been found in both Europe and North America.
Climatius was an active swimmer judging from its powerful caudal fin and abundant stabilizing fins, and probably preyed on other fish and crustaceans. Its lower jaw was lined with sharp teeth which were replaced when worn, but the upper jaw had no teeth. It also had large eyes, suggesting that it hunted by sight.
Although it was a small fish, at 7.5 centimetres (3 in), to discourage predators, Climatius sported a total of fifteen sharp spines. There was one spine each on the paired pelvic and pectoral fins, and on the aingle anal and two dorsal fins, and a further four pairs without fins on the fish's underside.