It was written by members Tony Banks, Phil Collins, and Mike Rutherford, produced by all three alongside Hugh Padgham, and released as the third single from their eponymous 1983 studio album in January 1984.

Its accompanying music video depicts the members of Genesis as a group of Mexican men unsuccessfully attempting to get their passports approved, and shows them in ponchos and sombreros.

"[6] The midsection features piano and a trumpet played by Collins, as well as sound effects, such as traffic noises and a telephone ringing, recorded by Banks's E-mu Emulator sampler.

[8] For Reader's Digest, Jeremy Helligar included "Illegal Alien" on a list of racist songs and wrote that "the fact that it exists at all proves that undervaluing Mexicans has been an American theme for decades".

[9] Shannon Sweet of the San Antonio Current wrote that it "goes full-on racist" and "tackles every Hispanic stereotype that exists", while Ryan Reed of Stereogum called it "face-palm filler" and a "borderline-racist border-crossing sing-along".

[13] The Ringer's Steven Hyden called it the most infamous song from Genesis, and described Collins's vocals as "a grotesque Speedy Gonzales–level caricature of a tequila-swilling Mexican immigrant".

Club's Steven Hyden wrote in 2008 that he "really loved" "Illegal Alien" in spite of it being "really offensive", "racist", and "tough not to cringe" at, due to its "irresistible" melody and its lyrics "set[ting] the scene pretty vividly".

[6][16][13] On his 2018 list of politically incorrect songs, USA Today's Patrick Ryan wrote that, while the message of "Illegal Alien" was "seemingly well-intentioned", the stereotypes depicted in its music video painted it in a racist light.

Club wrote that, while the video for "Illegal Alien" "touch[ed] on pretty much every Mexican stereotype, like a check list", it was "too self-consciously silly and plain old fun to be truly offensive".