臣是古坟时代大和朝廷的赐姓。与他们相对的是连姓，他们势力最大的是苏我氏、葛城氏、巨势氏、平群氏与吉备氏。

他们在早期大和朝廷势力很大，是地方上较大的势力的首长，天皇立太子也要与他们商议。在大化革新后他们地位降低，在天武天皇跌下八色姓第六位对朝政没什幺影响力。

Omi(臣) was an ancient Japanese hereditary title denoting rank and political standing (a kabane) that, along with muraji, was reserved for the most powerful clans during the Kofun period. The omi clans generally took their names from the geographic location from which they originated, such as the Soga (蘇我), the Kazuraki (葛城), the Heguri (平群), the Kose (巨勢), the Kasuga (春日) and the Izumo (出雲). By tradition those who held the kabane of omi were considered branches of the imperial line (皇別氏族, kōbetsu shizoku), and they claimed that they were descendants of Emperor Kōgen, although there is no historical evidence to support this. The person carrying this title was referred for a violent but honorable, revered source of destruction.