Illegal Alien

Illegal Alien or Illegal Aliens may refer to:
 * Alien (law), legal concept of aliens
 * Illegal alien, the statutory and legal term used in some countries for an illegal immigrant or other unauthorized resident
 * Illegal aliens (Library of Congress Subject Heading), a cause of controversy in 2016
 * Enemy alien

Entertainment

 * Illegal Aliens (film), a 2007 film starring Anna Nicole Smith and Chyna
 * Illegal Aliens (novel), a 1989 science fiction novel by Nick Pollotta and Phil Foglio
 * Illegal Alien (Sawyer novel), a 1997 science fiction novel by Robert J. Sawyer
 * Illegal Alien (Tucker and Perry novel), a 1997 Doctor Who novel by Mike Tucker & Robert Perry
 * Illegal Alien, a graphic novel by James Robinson
 * "Illegal Alien" (song), a track on the album Genesis by Genesis (1983)