Warndarrang (waɳʈaraŋ), also spelt Warndarang, Wanderang, Wandaran, and other variants is an extinct Aboriginal Australian language in the Arnhem family, formerly spoken by the Warndarrang people in southern Arnhem Land, along the Gulf of Carpentaria. The last speaker was Isaac Joshua, who died in 1974, while working with the linguist Jeffrey Heath.

Warndarrang is characterised by an unusually simplified nominal case system but highly intricate pronominal and demonstrative systems. It is a primarily prefixing language with agglutinating verbal complexes and relatively straightforward syntax.

Warndarrang is closely related to Mara, which was traditionally spoken to the south of Warndarang and today has a handful of speakers. The languages Alawa and Yugul, spoken to the west of Warndarrang and both apparently extinct, are also related.

Heath's Warndarang grammar contains a 100-page grammatical description, a handful of texts, and a brief wordlist. A Warndarang story of the Hodgson Downs massacre is published separately, and both Margaret Sharpe and Arthur Capell collected material in the 1960s and 1940s, respectively, much of which is unpublished but was incorporated into Heath's grammar.

Warndarang is a member of the Gunwinyguan family, the second-largest Australian language family after Pama–Nyungan. Warndarang is an extinct language — the last speaker died in 1974 — but was traditionally spoken along the Gulf of Carpentaria, in Arnhem Land (Northern Territory, Australia) near the mouths of the Roper, Phelp, and Rose Rivers. The term ɳuŋguɭaŋur, meaning "corroboree people," was used by Warndarang speakers to refer to the people in the Roper River area, though waɳʈaraŋ was used to refer to speakers of Warndarang specifically.

Within the Gunwinyguan languages, Warndarang is most closely related to Mara, a language today spoken by only a handful of people. Warndarang and Mara, together with Alawa and Yugul, form what used to be known as the "Mara-Alawic family" and today is considered a subgrouping of the Gunwinyguan family. Mara was traditionally spoken to the south of Warndarang, along the coast and the Limmen Bight River, while Yugul and Alawa were spoken inland, to the west of Warndarang. Yugul and Alawa both appear to be extinct. Warndarang territory was bordered on the north by the languages Ngandi and Nunggubuyu, with which Warndarang had significant contact. Ngandi is extinct, though many Nunggubuyu children are semi-speakers.

The Warndarang people classified themselves into four patrilineal semimoieties used in ritual settings: mambali, muruŋun, wuʈal, and guyal (wuyal). Mambali and muruŋun were considered to be associated, as were wuʈal and guyal, enough so that a person of one semimoiety learned and was permitted to sing the traditional songs of the associated semimoiety. Each semimoiety was associated with a particular watering hole and animal totems (for example, muruŋun had the totem ŋarugalin, "dugong [Dugong dugon]"), though anybody could drink from the watering holes and a person was permitted to consume his or her totem. This structure is very similar to those of the Mara and Nunggubuyu people.

The majority of Warndarang material was collected by the linguist Jeffrey Heath in 1973 (two days) and 1974 (fifteen days) from a single informant, Isaac Joshua. Isaac was born in approximately 1904 in the Phelp River region, moving as a young man to work as a stockman with the Mara people. As such, he had spoken very little Warndarang in decades preceding Heath's arrival, speaking instead in Mara, English, Kriol, or Nunggubuyu, but proved to be a good informant, especially knowledgeable on flora-fauna and religiously significant terms. Brief work on Warndarang by Margaret Sharpe in the 1960s also used Isaac Joshua as the sole informant, though Arthur Capell's work in the 1940s used Isaac's brother, Joshua Joshua. An elderly woman by the name of Elizabeth Joshua remembered a small amount of Warndarang, and Heath checked a few points with her after Isaac's death.