神圣之人（Homo sacer,拉丁语，字面意为“分别的人”）是罗马法中的一个刑法概念。这样的人，一方面被驱逐出人类社会，因此不受法律保护，任何人都可以杀死他而不构成犯罪。但另一方面他又被视为神圣的，专属于某个或某些神祇，因此不能用来作为人祭的祭品（在有此习俗的社会里，人祭是最高等级的祭品）。

神圣性的取得是因为这样的人曾经以神之名起誓：「若违誓言，愿受神罚」。当他违背誓言时起，就被视为该神祇的财产。因为他已是该神祇的财产，便不能再属于别的神祇，因此不能当作人祭的祭品；也不能再属于人类社会，因此不受人类社会的法律保护；若他被杀了，便被解读为该神祇透过凶手之手降罚，杀人者因此无罪。

Homo sacer (Latin for "the sacred man" or "the accursed man") is a figure of Roman law: a person who is banned and may be killed by anybody, but may not be sacrificed in a religious ritual.

The meaning of the term sacer in Ancient Roman religion is not fully congruent with the meaning it took after Christianization, and which was adopted into English as sacred. In early Roman religion sacer, much like the Hebrew קָדוֹש qadoš, denotes anything "set apart" from common society and encompasses both the sense of "hallowed" and that of "cursed". This concept of the sacred is more in line with the Islamic notion of haram. The homo sacer could thus also simply mean a person expunged from society and deprived of all rights and all functions in civil religion. Homo sacer is defined in legal terms as someone who can be killed without the killer being regarded as a murderer; and a person who cannot be sacrificed. The sacred human may thus be understood as someone outside the law, or beyond it. In the case of certain monarchs in western legal traditions, the sovereign and the Homo Sacer have conflated.