Hoplocetus is an extinct genus of raptorial cetacean of the sperm whale superfamily, Physeteroidea.

[1] The teeth of Hoplocetus are massive (95–150 mm in length; 27–47 in maximum diameter), robust and have a short enamel cap on the crowns.

[3] They are somewhat larger than those of modern orcas[4] but considerably smaller than those of macroraptorial sperm whales, such as Zygophyseter, as well as those of Scaldicetus caretti.

[5] They display a large degree of abrasion, suggesting a highly predatory niche comparable to that of modern orcas.

[3] These teeth features also characterize the other extinct toothed whale genera, Diaphorocetus, Idiorophus and Scaldicetus, sometimes placed with Hoplocetus in the subfamily Hoplocetinae.