An expatriate (in abbreviated form expat) is someone temporarily or permanently in a country and culture other than that of their upbringing and/or legal residence. The word comes for the Latin ex (out of) and patria (country), and is sometimes misspelt as ex-patriot, due to its pronunciation.

The term is often used in the context of Westerners living in non-Western countries, athough there are instances of Westerners living in other Western countries, such as Australians living in the United Kingdom and British people living in Spain.

Expatriate culture, such as that of the British in India or East Africa, can become quite distinct, and is often subject to parody and ridicule. Expatriates often find upon returning to their country of origin that it has developed in ways they find incomprehensible; this leads to a sense of alienation and anomie. Similarly, they are viewed by their fellow citizens as foreigners. They can be described as "when-I"s or "when-we"s, because they start every sentence with anecdotes about "when I" or "when we" lived in another country, reminiscing about their lifestyles overseas.

The difference between an expatriate and an immigrant is that immigrants commit themselves to becoming a part of their country of residence, whereas expatriates see themselves, and are perceived, as living in a foreign land. While Europeans or North Americans living in the Middle East and Asia may marry local people and have children, most see no advantage in adopting citizenship of their host countries, usually because dual citizenship is not permitted, but also because it may not be available to them at all. In countries like Saudi Arabia, expatriates are required to live in segregated compounds, meaning that integration into their host country's society is not an option.