Some exceptionally unsettling elements were thrown together to create the Xenomorph when it first appeared in Ridley Scott's 1979 horror sci-fi, "Alien." Spliced from the nightmares of artist H.R.

The "Alien" franchise is an undeniable classic — a staple of the sci-fi/horror genre. The series features humans fighting for their lives as they're pitted against killer aliens with acidic blood.