As Amazon's book editors released their 100 Best Sci-Fi/Fantasy Books list, CNN asked them to pick their 20 "must-haves" for any serious science fiction/fantasy reader's book shelf. "American Gods" by Neil Gaiman is a tale of old gods versus the new gods of Internet, television, credit cards and more. Click through the gallery to see the rest of Amazon's classic 20 picks, listed in alphabetical order by title:
Escaping slavery, Cazaril returns to the royal household to tutor a princess whose brother is heir to the throne in "The Curse of Chalion" by Lois McMaster Bujold. The people who enslaved him are now in positions of power, and sinister forces are also at work against the royal household.
Like Harry Potter, Will Stanton from "The Dark is Rising" (by Susan Cooper) learns he has more power than he previously understood. The last of the Old Ones, it's his destiny to fight the forces of evil.
Margaret K. McElderry Books
A Hugo and Nebula Award winner, "Dune" by Frank Herbert is the first book in the series about the the planet Arrakis, the struggle for power in an interstellar empire and a young man at the center of the fighting.
A Hugo and Nebula Award winner, the young adult book "Ender's Game" by Orson Scott Card tells the story of a world preparing for war. Fearful of another alien attack on the planet, the government is breeding geniuses and training them from childhood as soldiers. Tensions arise in a family when one sibling is chosen for the school and two others are not.
"The Forever War" by Vietnam veteran Joe Haldeman tells the story of war and the complication of solders traveling quickly through space, only to find upon their return home that the world has aged at normal time. William Mandella returns home after a year at war, while 27 years have passed at home. Unable to adjust to Earth, he re-enlists. A Hugo and Nebula award winner, Haldeman's classic has been called a great war novel of any genre.
St. Martin's Griffin
No matter that many may think "A Game of Thrones" is only a hugely popular television show . This book by by George R.R. Martin is a world where the seasons are out of whack and sinister magic is brewing beyond the protective Wall the failing king created to protect his kingdom.
In "Good Omens: The Nice and Accurate Prophecies of Agnes Nutter, Witch" by Terry Pratchett and Neil Gaiman, the world is about to end. But the angels and demons who populate the Earth aren't so interested anymore in helping to make the Rapture happen. They're just not sure where to find the Antichrist, an 11-year-old boy living in the same town they are.
In the future portrayed in "The Handmaid's Tale" by Margaret Atwood, women are not allowed to read and do not control their bodies anymore. They simply exist to serve men, whether to serve as their chaste wives, their housekeepers or their handmaids --where they are only valued if they can give birth.
At the start of "Harry Potter and the Sorcerer's Stone" by J.K. Rowling, Harry has no idea that he's destined to be a great wizard. His parents are dead, and his abusive aunt and uncle have kept his history a secret. That is, until he's accepted to Hogwarts School of Witchcraft and Wizardry and starts to learn about his noble heritage and destiny.
What is the answer to life, the universe and everything? "The Hitchhiker's Guide to the Galaxy" by Douglas Adams will answer that question, and more. Like what happens when the Earth to demolished to make way for an intergalactic freeway? And what's the most useful thing for an interstellar hitchhiker to carry?
Bilbo Baggins, the star hobbit in "The Hobbit" by J.R.R. Tolkien, doesn't want to leave his home (or really, even his pantry). But the wizard Gandalf and a band of dwarfs coming calling, and an adventure that has captured fans for generations was born.
Houghton Mifflin Harcourt
In the classic "I, Robot" by Isaac Asimov, this dean of science fiction lays out the laws by which robots must live in an interconnected series of stories. Since not all robots follow the rules, the human species itself may be in jeopardy.
In "The Left Hand of Darkness," Ursula K. Le Guin challenges readers to defy gender stereotypes. While human Genly Ai has been sent to the planet Winter to bring its people back into civilization, he must bridge the gaps between his culture and a planet where people can be of no gender or both.
No, Amazon didn't forget "The Lord of the Rings" by J.R.R. Tolkien. If you haven't read "The Hobbit" first, go pick it up. Then turn to "The Lord of the Rings" to find out what happens next. (No superfans, we aren't going spoil it for the newbies.)
Before actor Matt Damon filmed "The Martian," Andy Weir wrote the classic science fiction novel about astronaut Mark Watney walking on Mars -- and trying not to die there. Once his crew evacuates, thinking him dead, Watney must use his wits to survive.
"Outlander" by Diana Gabaldon tells the story of Claire Beauchamp Randall, who is married to one man in the 1900s and traveling through time and falling in love with another man in the 1700s. The historical time travel books are now the basis of a Starz original series.
A member of the lower-ranking "Red" class, Darrow finds that all is not what it seems in the futuristic Mars portrayed in "Red Rising" by Pierce Brown. Recruited as a revolutionary after his wife is executed by the government, Darrow is determined to overthrow the oppressive regime that has kept him down.
In "The Sparrow" by Mary Doria Russell, Jesuit priest and linguist Emilio Sandoz is the leader of a team of scientists and explorers on an expedition to a planet already inhabited by two races. His journey from landing in 2016 to a Vatican inquest in 2060 shows the impact of first contact on the inhabitants and the explorers.
First published in 1895, "The Time Machine" by H.G. Wells set the stage for much science fiction and time travel stories to follow.