If you want details of aliens or spacecrafts ranging from the popular ALF to the lesser-known Zazzala, this is the guide. Approximately 300 alphabetically arranged entries treat heroes and villains from comic books, sf magazines, TV shows, toys, radio, video games, trading cards, and films. The author, who also wrote the Encyclopedia of Superheroes and the Encyclopedia of Monsters, tried not to repeat entries from his other books and concentrated on characters that are well known. But also included are "wonderfully obscure" creations, works by unknown authors, and characters that are "fascinating."
Each entry describes the first appearance of the character or craft and its physical characteristics. For example, Battlestar Galactica traces its origin to a 1978 ABC-TV series. Usually entries are less than a page, with some especially famous stories (Superman, Gobots) running to three pages or more. An introductory guide explains media codes used in entries (e.g., Coneheads lists "TV, MP, C," meaning that it was first a TV show, then a motion picture, and then a comic book adaptation). More than 100 black-and-white drawings and photos add to the book's appeal. Five appendixes list the overflow of aliens and worlds from Star Trek, Star Wars, Outer Limits, and comic books. A bibliography is followed by an extensive index of authors, titles, actors, media, type of character (doctor, professor, princess), and subjects.