Onthophagus vacca is a species of dung beetles in the Onthophagini tribe of the wider scarab beetle family, Scarabaeidae.

 Onthophagus vacca can reach a length of . Pronotum is densely punctured. The first pair of legs are powerful, with three teeth on the outside and fit to digging. Head, legs and pronotum are black or dark green, while elytrae are yellowish with small green dots, often merged into longitudinal stripes.

Distribution: This species is present in most of Southern Europe, Western Asia and North Africa. It was introduced to Australia in 2014 to improve processing of cattle dung.