All species are dangerous (Pseudechis signifying "like a viper", Greek echis) and can inflict a potentially lethal bite.

Most snakes in this genus reach about 2 m (6.6 ft) in total length (including tail), and vary in colour.

All species of Pseudechis lay eggs with the exception of the red-bellied black snake P. porphyriacus which is viviparous.

The systematic revision of the elapid family by George Albert Boulenger in 1896 allied the descriptions of eight species, and by 1933 the number totalled taxa assigned to the genus.

The examination of a large series of specimens of the king brown Pseudechis australis was undertaken by Laurie Smith, recognising clinal variability within the population and separating a form with significant distinctions in morphology as a sixth species of the genus, Pseudechis butleri.