The Yolngu or Yolŋu (IPA: [ˈjuːlŋʊ] or [ˈjuːŋuːl]) are an aggregation of Aboriginal Australian people inhabiting north-eastern Arnhem Land in the Northern Territory of Australia. Yolngu means "person" in the Yolŋu languages. The terms Murngin, Wulamba, Yalnumata, Murrgin and Yulangor were formerly used by some anthropologists for the Yolngu.

All Yolngu clans are affiliated with either the Dhuwa (also spelt Dua) or the Yirritja moiety. Prominent Dhuwa clans include the Rirratjiŋu and Gälpu clans of the Dangu people, while the Gumatj clan is the most prominent in the Yirritja moiety.

The ethnonym Murrgin gained currency after its extensive use in a book by the American anthropologist W. Lloyd Warner, whose study of the Yolngu, A Black Civilization: a Social Study of an Australian Tribe (1937) quickly assumed the status of an ethnographical classic, considered by R. Lauriston Sharp the "first adequately rounded out descriptive picture of an Australian Aboriginal community." Norman Tindale was dismissive of the term, regarding it, like the term Kurnai, as "artificial", having been arbitrarily applied to a large number of peoples of northeastern Australia. The proper transliteration of the word was, in any case, Muraŋin, meaning "shovel-nosed spear folk", an expression appropriate to western peripheral tribes, such as the Rembarrnga of the general area Warner described.

For Tindale, following recent linguistic studies, the eastern Arnhem Land tribes constituting the Yolngu lacked the standard tribal structures evidenced elsewhere in Aboriginal Australia, in comprising several distinct socio-linguistic groups in an otherwise integral cultural continuum. He classified these as the Yan-nhaŋu, Djinang, Djinba, Djaŋu, Dangu, Rembarrnga, Ritharngu, Dhuwal and the Dhuwala.

Warner had deployed the term "Murngin" to denote a group of peoples who shared, in his analysis, a distinctive form of kinship organisation, describing their marriage rules, subsection system and kinship terminology. Other researchers in the field quickly contested his early findings. T. Theodor Webb argued that Warner's Murngin actually referred to one moiety, and could only denote a Yiritcha mala, and dismissed Warner's terminology as misleading. A. P. Elkin, comparing the work of Warner and Webb, endorsed the latter's analysis as more congruent with the known facts.

Wilbur Chaseling used the term "Yulengor" in the title of his 1957 work.

Since the 1960s, the term Yolŋu has been widely used by linguists, anthropologists and the Yolŋu people themselves. The term applies to both the sociocultural unit and the language dialects within it.

Yolngu comprise several distinct groups, differentiated by the languages and dialects they speak, but generally sharing overall similarities in the ritual life and hunter-gathering economic and cultural lifestyles in the territory of eastern Arnhem land. Early ethnographers studying the Yolngu applied the nineteenth-century concepts of tribe, horde and phratry to classify and sort into separate identities the units forming the Yolngu ethnocultural mosaic. After the work of Ian Keen in particular, such taxonomic terminology is increasingly seen as unsuitable and inadequate because of its eurocentric assumptions. Specialists are undecided, for example, whether the languages spoken by the Yolngu amount to five or eight, and one survey arrived at eleven distinct "dialect" groups.