The impala or rooibok (Aepyceros melampus, lit. 'black-footed high-horn' in Ancient Greek) is a medium-sized antelope found in eastern and southern Africa. The only extant member of the genus Aepyceros, and tribe Aepycerotini, it was first described to Europeans by German zoologist Hinrich Lichtenstein in 1812. Two subspecies are recognised—the grassland-dwelling common impala (sometimes referred to as the Kenyan impala), and the larger and darker black-faced impala, which lives in slightly more arid, scrubland environments. The impala reaches 70–92 cm (28–36 in) at the shoulder and weighs 40–65 kg (88–143 lb). It features a glossy, reddish brown coat. The male's slender, lyre-shaped horns are 45–92 cm (18–36 in) long.

Active mainly during the day, the impala may be gregarious or territorial depending upon the climate and geography. Three distinct social groups can be observed: the territorial males, bachelor herds and female herds. The impala is known for two characteristic leaps that constitute an anti-predator strategy. Browsers as well as grazers, impala feed on monocots, dicots, forbs, fruits and acacia pods (whenever available). An annual, three-week-long rut takes place toward the end of the wet season, typically in May. Rutting males fight over dominance, and the victorious male courts females in oestrus. Gestation lasts six to seven months, following which a single calf is born and immediately concealed in cover. Calves are suckled for four to six months; young males—forced out of the all-female groups—join bachelor herds, while females may stay back.

The impala is found in woodlands and sometimes on the interface (ecotone) between woodlands and savannahs; it inhabits places near water. While the black-faced impala is confined to southwestern Angola and Kaokoland in northwestern Namibia, the common impala is widespread across its range and has been reintroduced in Gabon and southern Africa. The International Union for Conservation of Nature (IUCN) classifies the impala as a species of least concern; the black-faced subspecies has been classified as a vulnerable species, with fewer than 1,000 individuals remaining in the wild as of 2008.

The first attested English name, in 1802, was palla or pallah, from the Tswana phala 'red antelope'; the name impala, also spelled impalla or mpala, is first attested in 1875, and is directly from Zulu. Its Afrikaans name, rooibok 'red buck', is also sometimes used in English.

The scientific generic name Aepyceros (lit. 'high-horned') comes from Ancient Greek αἰπύς (aipus, 'high, steep') + κέρας (keras, 'horn'); the specific name melampus (lit. 'black-foot') from μελάς (melas, 'black') + πούς (pous, 'foot').

The impala is the sole member of the genus Aepyceros and belongs to the family Bovidae. It was first described by German zoologist Martin Hinrich Carl Lichtenstein in 1812. In 1984, palaeontologist Elisabeth Vrba opined that the impala is a sister taxon to the alcelaphines, given its resemblance to the hartebeest. A 1999 phylogenetic study by Alexandre Hassanin (of the National Centre for Scientific Research, Paris) and colleagues, based on mitochondrial and nuclear analyses, showed that the impala forms a clade with the suni (Neotragus moschatus). This clade is sister to another formed by the bay duiker (Cephalophus dorsalis) and the klipspringer (Oreotragus oreotragus). An rRNA and β-spectrin nuclear sequence analysis in 2003 also supported an association between Aepyceros and Neotragus. The following cladogram is based on the 1999 study:

Up to six subspecies have been described, although only two are generally recognised on the basis of mitochondrial data. Though morphologically similar, the subspecies show a significant genetic distance between them, and no hybrids between them have been reported.

According to Vrba, the impala evolved from an alcelaphine ancestor. She noted that while this ancestor has diverged at least 18 times into various morphologically different forms, the impala has continued in its basic form for at least five million years. Several fossil species have been discovered, including A. datoadeni from the Pliocene of Ethiopia. The oldest fossil discovered suggests its ancient ancestors were slightly smaller than the modern form, but otherwise very similar in all aspects to the latter. This implies that the impala has efficiently adapted to its environment since prehistoric times. Its gregarious nature, variety in diet, positive population trend, defence against ticks and symbiotic relationship with the tick-feeding oxpeckers could have played a role in preventing major changes in morphology and behaviour.