| Named By: | Francisco P. Moreno & Alcides Mercerat in 1891 |
| Time Period: | Miocene |
| Location: | Argentina, Santa Cruz Province |
| Size: | Up to 2.8 metres tall |
| Diet: | Carnivore |
| Fossil(s): | Several specimens, usually of the legs and feet, but some vertebrae and skull material are also known |
| Classification: | | Chordata | Aves | Cariamae | Phorusrhacidae | Brontornithinae | |
| Also known as: | | Brontornis platyonyx | Rostrornis floweri | |
Brontornis is an extinct genus of giant flightless predatory birds that lived in Patagonia. The only species currently accepted as valid is B. burmeisteri. It has traditionally been placed in the family Phorusrhacidae, nicknamed "terror birds" for their large size and predatory lifestyle, more specifically the subfamily Brontornithinae, which contains the extremely large and heavy-set phorusrhacids.