| Named By: | Brandt in 1843 |
| Time Period: | Miocene-Pliocene |
| Location: | Eurasia and North America |
| Size: | Around 4.5 meters long |
| Diet: | Filter feeder |
| Fossil(s): | Multiple specimens |
| Classification: | | Chiordata | Mammalia | Cetacea | Mysticeti | Cetotheriidae | |
| Also known as: | | Cetotherium rathkei | |
Cetotherium ("whale beast") is a genus of cetaceans from the family Cetotheriidae.