The Tehuantepec jackrabbit (Lepus flavigularis) (Spanish: liebre de Tehuantepec) is a medium-sized species of hare in the family Leporidae that is endemic to eastern Oaxaca, Mexico. It exists in three separated populations, living on grassy dunes and savannas, and is herbivorous, mainly eating grasses. It is not territorial. Most active at night, it will feed for most of the time and occasionally groom or socialize with other hares, spending the daytime resting on beds of grass or shrubs, or under nopales. They are polygynous and breed for most of the year, from February to December, producing one to four young per breeding season. Predators include snakes, dogs, cats, coyotes, and gray foxes.

The Tehuantepec jackrabbit is the most endangered of the hares, with less than 300 mature individuals estimated as of 2019, and is threatened by various factors in its small distribution, including poaching, habitat loss and fragmentation, a small population size, and genetic isolation. Changing agricultural practices, loss of diversity in flora, and competition for food are also factors in the species' decline. It is recognized as endangered both by the International Union for the Conservation of Nature (IUCN) and local authorities in Mexico through the Official Journal of the Federation, and efforts to monitor and implement conservation actions have been ongoing.

Lepus flavigularis was first described in 1844 by Johann Andreas Wagner in a reassessment of Johann Georg Wagler's 1830 description of several Mexican hares. The species was noted as displaying the "extremes" in coloration of each of the two other hares in question: the white-sided jackrabbit (Lepus callotis) and the black-tailed hare (Lepus nigricaudatus), the latter of which is now synonymous with L. callotis. The type locality was given simply as Mexico; American zoologist Daniel Giraud Elliot later restricted this in a 1905 checklist of mammals to San Mateo del Mar, Tehuantepec [City], Oaxaca, Mexico. At the time, it was considered a subspecies of the white-sided jackrabbit (then known as the "beautiful-eared jack rabbit"). L. flavigularis was later classified as a distinct species by Edward William Nelson following a numerical analysis of morphological traits in 1909.

Besides the common name Tehuantepec jackrabbit, so called for its type locality, it is also known in Spanish as the liebre tropical, or tropical hare.

The Tehuantepec jackrabbit is closely related to the white-sided jackrabbit. They are grouped together in a subclade separate from other American members of Lepus, such as the black-tailed (Lepus californicus) and white-tailed (Lepus townsendii) jackrabbits. The next-closest related species to L. flavigularis, the antelope jackrabbit (Lepus alleni), likely diverged from the white-sided jackrabbit when a population of the latter species became isolated along the western coastal plains of Mexico. Similarly, L. flavigularis diverged from the white-sided jackrabbit following isolation in southeastern Oaxaca. None of these three species overlap in distribution.

L. flavigularis has 48 diploid chromosomes, a number shared by every other member of Lepus. The species' fundamental number of chromosomes is 88, and it has a large X chromosome, a trait shared by the antelope jackrabbit and black-tailed jackrabbit. There are no subspecies of the Tehuantepec jackrabbit, and no fossils are known. The population in the Santa María del Mar area of Juchitán de Zaragoza municipality, the northernmost population of the species, is separated by water and human-built structures from other populations of the species, and has very little gene flow, resulting in its separation into a distinct clade.

Lepus flavigularis is a medium-sized hare, ranging in length from 22.2 to 24.0 inches (56.5 to 61 cm). The chest and neck are yellowish in color, and it can be distinguished from other species by two black stripes that run from the base of the ears to the nape, and by its white flanks. This same coloration of the nape is also noted in several subspecies of the black-tailed jackrabbit. The tail measures from 2.6 to 3.7 inches (65 to 95 mm) and is black above and white underneath. Adults weigh from 3.7 to 6.4 pounds (1.7 to 2.9 kg). The ears range in size from 4.3 to 4.7 inches (110 to 120 mm) and the hind foot from 4.5 to 5.3 inches (115 to 134 mm). Its skull is elongated, and among the Mexican hares, its tympanic bullae (bone structures that enclose the middle and inner ear) are the smallest.

The Tehuantepec jackrabbit resides in tropical dry savannas dominated by native grasses in the genera Bouteloua and Paspalum with an overstory of sparse bushes of nanche (Byrsonima crassifolia), and scattered trees of morro (genus Crescentia). Generally, it tends towards habitats without dense vegetation, but can be flexible depending on the available resources. It is also found in coastal grassy dunes alongside the plants Opuntia decumbens, Opuntia tehuantepecana, and Sabal mexicana. It occurs from sea level up to an elevation of c. 2,185 feet (666 m).