In his original 1816 description of the emu, Louis Pierre Vieillot used two generic names; first Dromiceius, then Dromaius a few pages later.

Most modern publications, including those of the Australian government,[5] use Dromaius, with Dromiceius mentioned as an alternative spelling.

[5] The Dromiceius spelling was the basis for Dale Russell's 1972 naming of the dinosaur Dromiceiomimus.

The following species and subspecies are recognized: A number of other emu fossils from Australia described as separate species are now regarded as chronosubspecies at best, given the considerable variation even between living individuals.

[10] There are also some unidentifiable remains of emu-like birds from rocks as old as the middle Miocene.