| Named By: | Fraas in 1904 |
| Time Period: | Middle Eocene |
| Location: | Egypt. - Mokattam Formation |
| Size: | 2.5 meters long |
| Diet: | Carnivore |
| Fossil(s): | Single specimen |
| Classification: | | Chordata | Mammalia | Cetacea | Archaeoceti | Protocetidae | |
Protocetus atavus ("first whale") is an extinct species of primitive cetacean from Egypt. It lived during the middle Eocene period 45 million years ago.
The first discovered protocetid, Protocetus atavus was described by Fraas 1904 based on a cranium and a number of associated vertebrae and ribs found in middle Lutetian Tethyan marine limestone from Gebel Mokattam near Cairo, Egypt.