| Named By: | Edward Drinker Cope in 1873 |
| Time Period: | Late Cretaceous, 87-81 Ma |
| Location: | USA |
| Size: | Up to about 6 meters long |
| Diet: | Planktonic filter feeder |
| Fossil(s): | Partial remains |
| Classification: | | Chordata | Actinopterygii | Pachycormiformes | Pachycormidae | |
| Also known as: | | Portheus gladius | Protosphyraena gladius | |
Bonnerichthys is a genus of fossil fishes within the family Pachycormidae that lived during the Late Cretaceous Period Fossil remains of this taxon are known from the Smoky Hill Member of the Niobrara Chalk Formation of Kansas (Late Coniacian-Early Campanian, about 87-81 million years ago). It grew to around 20 feet in length, though not quite as large as the related Leedsichthys from the Jurassic of Europe which likely grew up to 30 feet.