无国籍（英语：Statelessness），是指某人不被任何一个国家的法律认为是其国民从而没有任何国籍，或者说不属于任何国家的状态。无国籍人士在国际上不享受任何国家的外交保护。

判定无国籍人士要注意以下情况：

In law, statelessness is the lack of nationality, or the absence of a recognized link between an individual and any state.

A stateless person is someone who is "not considered as a national by any state under the operation of its law"; he or she has no citizenship or nationality. Some stateless persons are also refugees. However, not all refugees are stateless, and many persons who are stateless have never crossed an international border.