Onthophagus is a genus of dung beetles in the Onthophagini tribe of the wider scarab beetle family, Scarabaeidae. It is the most species-rich and widespread genus in the subfamily Scarabaeinae (the ´true´ dung beetles), with a global distribution.

Etymology: The Genus name derives from the Greek onthos, meaning dung, and , meaning eater.

Taxonomy: This genus includes around 30 subgenera and over 2,200 species. Some of the former subgenera of Onthophagus (including Proagoderus, Diastellopalpus, Digitonthophagus, and Euonthophagus) are now widely recognized as genera.

Subgenera: These subgenera are in accordance with the Catalog of Life and the World Scarabaeidae Database (2023).

• Afrostrandius Moretto, 2009 - tropical Africa
• Altonthophagus Kabakov, 1990 - Palearctic
• Amphionthophagus Martín-Piera & Zunino, 1983 - Palearctic
• Bicornonthophagus Tagliaferri & Moretto, 2012 - tropical Africa
• Colobonthophagus Balthasar, 1935 - Palaearctic, Oriental
• Cryptonthophagus Dierkens, 2022 - tropical Africa
• Drepanonthophagus Dierkens, 2022 - tropical Africa
• Endrodius Balthasar, 1959 - Oriental
• Eremonthophagus Zunino, 1979 - Palearctic
• Exonthophagus Kabakov, 2006 - Palearctic
• Furconthophagus Zunino, 1979 - Palaearctic, Oriental, tropical Africa
• Gibbonthophagus Balthasar, 1935 - Palaearctic, Oriental
• Gonocyphus Lansberge, 1885 - tropical Africa
• Hikidaeus Ochi & Kon, 2016 - Oriental
• Indachorius Balthasar, 1941 - Palaearctic, Oriental
• Indonthophagus Kabakov, 2006 - Palaearctic, Oriental, tropical Africa
• Macronthophagus Ochi, 2003 - Palaearctic, Oriental
• Matashia Matsumura, 1938 - Palaearctic, Oriental
• Micronthophagus Balthasar, 1963 - Oriental, Palaearctic, tropical Africa
• Onthophagiellus Balthasar, 1935 - Oriental
• Onthophagus Latreille, 1802 - worldwide
• Palaeonthophagus Zunino, 1979 - Palearctic
• Paraphanaeomorphus Balthasar, 1959 - Palaearctic, Oriental
• Parentius Zunino, 1979 - Palearctic
• Phanaeomorphus Balthasar, 1935 - Palaearctic, Oriental
• Pseudophanaeomorphus Ochi, 2007 - Oriental
• Serrophorus Balthasar, 1935 - Palaearctic, Oriental
• Sinonthophagus Kabakov, 2006 - Palearctic
• Strandius Balthasar, 1935 - Palaearctic, Oriental, tropical Africa
• Sunenaga Ochi, 2003 - Palaearctic, Oriental
• Trichonthophagus Zunino, 1979 - Palaearctic, Oriental, tropical Africa