In law, an alien is a person in a country who is not a citizen of that country.
Types of "alien" persons are:
- An alien who is legally permitted to remain in a country. On specified terms, this kind of alien may be called a legal alien of that country. This is a very broad category which includes tourists, guest workers, legal permanent residents and student visa resident aliens.
- An alien who has temporary or permanent residence in a country may be called a resident alienof that country. This is a subset of the aforementioned legal alien category.
- An alien who is visiting a country be called a nonresident alien of that country. This is a subset of the aforementioned legal alien category.
- An alien who is present in a country unlawfully or without the country's authorization is known as an illegal alien of that country.
- An enemy alien is an alien who is a national of an enemy country.
|The examples and perspective in this article may not represent a worldwide view of the subject. (December 2010)|
An "alien" in England was someone who was born outside of the monarch's dominions and who did not have allegiance to the monarch. Aliens were not allowed to own land and were subject to different taxes from subjects.
- In Australia, alien status is regarded in relationship to citizenship status. The following documents normally constitute evidence of Australian citizenship:
- a valid Australian passport
- a birth certificate issued by or on behalf of an Australian state or territory (only for those born before 20 August 1986)
- a certificate of evidence of Australian citizenship
- an Australian naturalisation certificate
- a certificate of Australian citizenship by descent
Some people who live in Australia are not Australian citizens - they are either permanent residents; temporary residents; or illegal residents (technically called "unlawful-non citizens"). Most non-citizens (i.e. those who lack citizenship documents) travelling to Australia must obtain a visa prior to travel. The only exceptions to this rule are members of the British royal family, and holders of New Zealand passports and citizenships who may apply for visas after travel according to the Trans-Tasman Travel Arrangement. 
- In the United Kingdom, alien means a person who is not:
- In U.S. law, an alien is "any person not a citizen or national of the United States." The U.S. Government's use of alien dates back to 1798, when it was used in the Alien and Sedition Acts. U.S. law makes a clear distinction between aliens and immigrants by defining immigrants as a subset of aliens. Although U.S. law provides no overarching explicit definition of the term "illegal alien," the term is used in many statutes and elsewhere (e.g., court cases, executive orders). U.S. law also uses the term "unauthorized alien." U.S. immigration laws do not refer to illegal immigrants, but in common parlance the term "illegal immigrant" is often used to refer to any illegal alien. Because at law, a corporation is a person, the term alien is not limited to natural humans because what are colloquially called foreign corporations are technically called alien corporations. Because corporations are creations of local state law, a foreign corporation is an out of state corporation.
On Latvian passports, alien is used for non-citizens (nepilsoņi): former citizens of USSR who don't have voting rights for the parliament of Latvia but have rights and privileges under Latvian law and international bilateral treaties, such as the right to travel without visas to both the EU and Russia, which is not possible for Latvian citizens.
"Alien" is derived from the Latin alienus, meaning stranger, alien, foreign.