Kelenken was a genus of terror birds that lived in what is now Argentina during the middle Miocene epoch. The type species, Kelenken guillermoi, is the largest terror bird yet discovered, with a skull length of 710 millimeters, including the 460 millimeter beak. The entire animal would have stood over 3 meters in height, and would have been among the heaviest of all birds, approaching the mass of the recently extinct Aepyornis.
While data on the habits and diet of this bird are not well known, it seems clear that it was the apex predator over most of its range, competing only with the also massive Argentavis. As Argentavis was capable of flight while Kelenken was not, however, it seems unlikely that they sought the same food sources.
Its closest modern relatives are the seriemas of South America, Cariama cristata and Chunga burmeisteri. Like Kelenken, these birds are carnivorous and have strongly hooked beaks similar in form to those of the terror birds. Unlike their larger forebears, however, the seriemas can fly, even if they are rather reluctant to do so.