Book excerpt: Aliens: They have taken the form of immigrants, invaders, lovers, heroes, cute creatures that want our candy or monsters that want our flesh. For more than a century, movies and television shows have speculated about the form and motives of alien life forms. Movies first dipped their toe into the genre in the 1940s with Superman cartoons and the big screen's first story of alien invasion (1945's The Purple Monster Strikes). More aliens landed in the 1950s science fiction movie boom, followed by more television appearances (The Invaders, My Favorite Martian) in the 1960s. Extraterrestrials have been on-screen mainstays ever since. This book examines various types of the on-screen alien visitor story, featuring a liberal array of alien types, designs and motives. Each chapter spotlights a specific film or TV series, offering comparative analyses and detailing the tropes, themes and cliches and how they have evolved over time. Highlighted subjects include Eternals, War of the Worlds, The X-Files, John Carpenter's The Thing and Attack of the 50-Foot Woman.