Third country national (TCN) is a term often used in the context of migration, referring to individuals who are in transit and/or applying for visas in countries that are not their country of origin (i.e. country of transit), in order to go to a destination country that is likewise not their country of origin. In the European Union, the term is often used, together with "foreign national" and "non-EU foreign national", to refer to individuals who are neither from the EU country in which they are currently living or staying, nor from other member states of the European Union.

In terms of employment, the term is often used to designate "an employee working temporarily in an assignment country, who is neither a national of the assignment country nor of the country in which the corporate headquarters is located."

In the US, it is often used to describe individuals of other nationalities hired by a government or government sanctioned contractor who represent neither the contracting government nor the host country or area of operations. This is most often those performing on government contracts in the role of a private military contractor. The term can also be used to describe foreign workers employed by private industry and citizens in a country such as Kuwait in which it is common to outsource work to non-citizens.