Gilbert's honeyeater (Melithreptus chloropsis), also known as the Swan River honeyeater or western white-naped honeyeater, is a passerine bird of the honeyeater family Meliphagidae native to southwestern Australia. A mid-sized honeyeater, it is olive-green above and white below, with a black head, nape and throat and a white patch over the eye and a white crescent-shaped patch on the nape. The bill is brownish-black and the eyes a dull red. The sexes have similar plumage.
A mid-sized honeyeater, Gilbert's honeyeater has olive-green upperparts and white underparts to the undertail. Both olive and white feathers have grey bases, which can be seen if the plumage is ruffled. White feathers on the flanks have dusky tips. It has a black head, nape and throat, a white patch over the eye, and a white crescent-shaped patch on the nape, which is thinner than that of other species. The bill is brownish-black and the eyes a dull red.
Within its range, its plumage is distinctive, rendering it unlikely to be confused with other species, apart from the related white-throated honeyeater (though this species are found much further north) or the Brown-headed honeyeater. Gilbert's honeyeater closely resembles the white-naped honeyeater; the plumage of the two is identical, except for the bare parts around the eye, which is pale-green to off-white in the former species, and red in the latter. Gilbert's honeyeater also has a longer bill and tarsus, and is slightly larger overall.