The Hakka (Chinese: 客家), also referred to as Hakka Chinese or Hakka-speaking Chinese, are an ethnic group and subgroup of Han Chinese whose principal settlements and ancestral homes are dispersed widely across the provinces of southern China and who speak a language that is closely related to Gan, a Chinese language spoken in Jiangxi province. They are differentiated from other southern Han Chinese by their dispersed nature and tendency to occupy marginal lands and remote hilly areas. The Chinese characters for Hakka (客家) literally mean "guest families".

The Hakka have settled throughout China and their presence is especially prominent in the landlocked border regions of Guangdong, Fujian and Jiangxi.

The traditional theory refers to that the Hakka mainly comprise descendants of Central Plains Chinese refugees fleeing social unrest, upheaval, and invasions. However, the Hakka were different in being late arrivals, moving from Central China into Southern China when the earlier groups of Han Chinese settlers in the south had already developed distinctive local identities and languages. Their migration path was also different, and they entered Guangdong, Guangxi and Fujian via Jiangxi province, instead of traversing Hunan or moving along the Fujian coast.

Today, substantial numbers of Hakka Chinese have migrated overseas to various countries throughout the world.

The Hakka, a group of nomadic peoples originating from the North, arrived in southern China much later than other southern Han Chinese populations. These earlier waves of southern Han Chinese colonists settled fertile lowlands, assimilated non-Han locals and expelled others like Tanka on coast and rivers, formed distinctive cultural identities and dialects. Consequently, the Hakka were forced to locate their settlements on marginal territories and relatively infertile land.

Studies show extensive unidirectional gene flow from the Hakkas to surrounding Han Chinese populations in the south resulting in a very close relationship. According to a 2009 study published in the American Journal of Human Genetics, the Hakkas are principally of Han Chinese descent, exhibiting an average genetic difference of 0.32% with other tested Han Chinese persons. Nonetheless, compared with other southern Han Chinese groups, the Hakka genetic profile exhibits a slight skew towards northern Han people.

The Hakka identify as Han Chinese and genetic studies show they are principally of Han ancestry, despite a recorded history of intermarriage with minority groups such as the Yao and the She. Furthermore, the Hakka language belongs to the Sinitic group of languages, being linguistically proximate to the Gan dialect of Jiangxi. The Hakka also exhibit traditional Confucian values, such as a respect for family, ancestor veneration, and a commitment to both learning and the ideals of a Confucian gentleman. Finally, they carry Han Chinese surnames and use Han Chinese naming conventions. Lingnan Hakka place names indicate a long history of the Hakka being Han Chinese. Like the Cantonese, they fiercely insisted on their Han identities and were principal movers of the Anti-Qing movement.

However, the Hakka differed in their lifestyles and their preferred mode of habitation - living in large communal fortress-like buildings (known as tulou) instead of residing in courtyard houses (or siheyuan). They also settled in marginal or hardscrabble hill land avoided by other Han Chinese subgroups, and in this regard, were considered similar to non-Han aborigines. They also exhibited gender egalitarianism to a greater degree than other southern Chinese.