Orson Scott Card creates a sort of taxonomy of strangers in the book Speaker for the Dead, which is part of the Ender's Game series. The categories of strangers are as follows:

  • Utlanning: the stranger that we recognize as being a human of our world, but of another city or country.

  • Framling: the stranger that we recognize as human, but of another world.

  • Ramen: the stranger that we recognize as human, but of another species. This categorization would apply to most of the aliens onboard the Enterprise in Star Trek: The Next Generation. Worf, for example, has many human characteristics but is clearly a different species altogether.

  • Varelse: the stranger that is not human. This category would apply to the alien in almost any horror film, such as the movie Alien.