The gerenuk, Litocranius walleri, also known as the Waller's gazelle, is a long-necked species of antelope found in dry thorn bush scrub and desert in East Africa, from Somalia, Djibouti and eastern Ethiopia through northern and eastern Kenya to northeastern Tanzania. The word gerenuk (pronounced with a hard g) comes from the Somali language, meaning "giraffe-necked". Gerenuk are sometimes also called the giraffe-necked antelope. It is the sole member of the genus Litocranius.
Gerenuks have a relatively small head for their body, but their eyes and ears are proportionately large. Only the males have horns and they also have a more muscular neck than females. Both sexes have ruddy brown coats with a paler underbelly . They have short, black tipped tails. From head to tail, the gerenuk is around 150 centimetres (59 in) long. Males are a little taller than females, at 89–105 cm (35–41 in) tall, with the females typically 80–100 cm (31–39 in) tall. The male is also heavier than the female, weighing 45 kilograms (99 lb), while females weigh around 30 kg (66 lb).
Gerenuks seldom graze but browse on prickly bushes and trees, such as acacias. They can reach higher branches and twigs than other gazelles and antelope by standing erect on their rear legs and stretching their elongated necks. They appear to favour the more tender leaves and shoots, but will also eat buds, flowers, fruit, and herbaceous plants. Gerenuks do not appear to drink water; they get enough water from the plants they eat. Because of this, they can survive in very dry habitats. Gerenuks are often prey for lions, cheetahs, jackals and leopards.