To determine the distribution and causes of extinction threat across functional groups of terrestrial vertebrates, we assembled a dataset on ecological traits for 18,016 species and tested, using phylogenetic comparative methods, which categories of habitat association, mode of locomotion, and feeding mode best predict extinction risk. We found that cave-dwelling amphibians, brachiating mammals (all of which are primates), aerial and scavenging birds, and pedal squamates are all disproportionately threatened with extinction. Across four vertebrate classes, agriculture, followed by logging, and then invasive species and disease are the most common risk factors of extinction. The most endangered species show simultaneous risk from multiple threat types. The disproportionate loss of species with certain functional traits, combined with increasing anthropogenic pressures, is likely to disrupt ecosystem functions globally if left unabated. A shift in focus from species- to trait-centric conservation practices will allow for the protection of at-risk functional diversity from regional to global scales.