The gerenuk[a] (Litocranius walleri), also known as the giraffe gazelle, is a long-necked, medium-sized antelope found in parts of East Africa.

Two types of colouration are clearly visible on the smooth coat: the reddish brown back or the "saddle", and the lighter flanks, fawn to buff.

The gerenuk was first described by Victor Brooke in 1879 on the basis of three male specimens procured on "the mainland of Africa, north of the island of Zanzibar".

[4] Brooke used the scientific name Gazella walleri, on the request of Gerald Waller (who provided the specimens) to name it after his deceased brother.

[4] The type locality was later corrected by John Kirk, who originally obtained the specimens on the "coast near the River Juba in southern Somalia" before giving them to Waller.

[3][9][10][11] In 1997 Colin Groves proposed that Litocranius is a sister taxon of the similarly long-necked dibatag (Ammodorcas clarkei), but withdrew from this in 2000.

[12] In 2013, Eva Verena Bärmann and colleagues (of the University of Cambridge) revised the phylogeny of tribe on the basis of nuclear and mitochondrial gene analysis.

[10][14] Two types of colouration are clearly visible on the smooth coat: the reddish brown dorsal parts (the back or the "saddle"), and the lighter flanks, fawn to buff.

Both are brachyodonts and share several facial and cranial features, along with a two-tone colouration of the coat and strong thick horns (only in males).

[10] A finer point of difference is the absence of an inward-curving lobe in the lower edge of the ear (near its tip) in the gerenuk.

[10] The Gerenuk stages of growth have a timespan from 4 months to 2.5 years: at four months, their shoulder height is about two-thirds of adult female, at six months their shoulder height is about three-quarters of adult female, at eight months their horn tips are clearly visible (about 1cm long), at one year their shoulder height is nearly equal to adult female but body more lightly built, their horns are slightly less than half ear-length, then curve, at two years their horns are about 1.5 times their ear length and the second curve becomes noticeable with the tips turning forwards, and finally at two and a half years the double curve in the horns are nearly completed.

[18] Major predators of the antelope include African wild dogs, cheetahs, hyenas, lions and leopards.