The Galah, Eolophus roseicapilla, is one of the most common and widespread cockatoos. It occupies open country in almost all parts of mainland Australia.

Galahs have a pale to mid grey back, a pink face and chest, and a lighter pink crest. Sexes are similar, differing only in eye colour: the male has a brown iris, the female red. Typical birds are about 35cm long and weigh between 300 and 400 grams.

The classification of the Galah is difficult. It was originally placed alone in the genus Eolophus, as there are clear morphological differences between the Galah and the white cockatoos that make up genus Cacatua (though older sources place the Galah in that genus). DNA evidence, however, conflicts with this, suggesting that the Galah is most closely related to the Cockatiel. It is thought that the ancestors of the Galah, the Cockatiel, and Major Mitchell's Cockatoo diverged from the main white cockatoo line at some stage prior to that group's main radiation.

Three subspecies are usually recognised. The south-eastern form, E. r. roseicapillus is clearly distinct from the paler-bodied Western Australian form, E. r. assimilis, although the extent and nature of the central hybrid zone remains undefined. Most pet birds outside Australia are the south-eastern form. The third form, E. r. kuhli, is found right across the northern part of the continent, tends to be a little smaller and is distinguished by differences in the shape of the crest and eye-ring, although its status as a true subspecies is uncertain.

Galahs are found in all Australian states, and are absent only from the dryest areas and the far north of Cape York Peninsula. They appear to have been self-introduced to Tasmania. They are common in some metropolitan areas, for example Perth, and common to abundant in open habitats which offer at least some scattered trees for shelter. The changes wrought by European settlement, a disaster for many species, have been highly beneficial for the Galah because of the clearing of forests in fertile areas and the provision of stock watering points in arid zones.

Galahs are highly social and very long lived: though they are sometimes kept as pets, this is not something to be undertaken lightly as they bond socially with their owners and may well outlive them.