"To Your Scattered Bodies Go" by Philip José Farmer
"To Your Scattered Bodies Go" starts off with a fairly simple premise — what would happen if everyone who ever lived was resurrected together?
Farmer's masterwork, which along with four sequels makes up the "Riverworld" saga, follows the unlikely interactions and adventures of both fictional characters and major historical figures.
Submitted by Reddit user TronGod666.
"The Shadow of the Torturer" by Gene Wolfe
"The Shadow of the Torturer" — the first installment in Wolfe's "The Book of the New Sun" series — follows Severian, a rising member of a Guild of torturers.
Severian is exiled for betraying his torturer’s vows by helping the woman he loves commit suicide, and begins a journey that forces questions on the nature of both reality and sanity.
Submitted by Reddit user teethteetheat.
"Anathem" by Neil Stephenson
One of the most academically fueled novels on any list of science-fiction, Stephenson's "Anathem" is based around a society that has corralled intellectuals — the avout — away to focus purely on study.
However, the lines between the avout and secular worlds seem to fade when an unforeseen crisis appears that could affect everyone.
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"Revelation Space" by Alastair Reynolds
When wealthy archaeologist and scientist Dan Sylveste discovers in 2551 that an ancient civilization on that planet Resurgam was mysteriously wiped out, he fears the same fate for humanity.
Through near-faster-than-light travel, "Revelation Space" interweaves several concurrent plots happening years and even decades apart.
Submitted by Reddit user KrytikalMasz.
"The Left Hand of Darkness" by Ursula K. Le Guin
Considered one of the first major works of feminist science-fiction, "The Left Hand of Darkness" chronicles a human’s attempt to convince a genderless race of aliens to join an intergalactic alliance.
Le Guin's depiction of the Gethenians and their constantly-cold planet Gethen — Winter, in English — allows for an exploration of a world without dualities.
Submitted by Reddit user aquadante.
"I, Robot" by Isaac Asimov
Fans of the Will Smith will find a lot to like about the source material, Asimov's nine short stories of the futuristic relationship between robots and humans.
Central to "I, Robot" is Asimov's "Three Laws of Robotics," a set of rules meant to ensure safety in his invented reality that serve as a driving theme for much of his work.
Submitted by Reddit user agent_of_entropy.
"Sirens of Titan" by Kurt Vonnegut
Vonnegut may be best known for "Slaughterhouse 5," but his second novel "The Sirens of Titan" is an interplanetary powerhouse that tackles everything from war and morality to the very purpose of human existence.
Along with the author's trademark wit and inventiveness, fans of Vonnegut's other works may recognize a certain alien race that makes an appearance.
Submitted by Reddit user kvigor.
"Contact" by Carl Sagan
Years after he entered America’s homes with his PBS program "Cosmos," Sagan published his novel "Contact," in which Earth receives several messages from extraterrestrial beings.
Many of the messages are based in the international language of mathematics, allowing the humans to reach out to and eventually interact with alien life.
Submitted by Reddit user lalalindsay.
"Red Mars" by Kim Stanley Robinson
Humanity takes to Mars to undergo a massive terraformation of the planet in the hopes of eventual colonization in the first novel of Robinson's "Mars Trilogy."
The entire trilogy spans centuries and focuses on scores of deeply developed characters, but this first installment delves into the scientific, sociological, and potentially ethical issues at play for the humans on Mars.
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"Pandora’s Star" by Peter F. Hamilton
In a universe where hundreds of planets are connected by a series of wormholes, astronomer Dudley Bose witnesses a star disappearing one thousand light-years away and goes to investigate.
Also in the mix are the Guardians of Selfhood, a cult that believes Bose’s mission is being sabotaged and manipulated by an entity called Starflyer.
Submitted by Reddit user Wrecktacular.
"The Mote in God’s Eye" by Larry Niven and Jerry Pournelle
In 3016, the Second Empire of Man spans hundreds of star systems thanks to the invention of the faster-than-light Alderson Drive — yet no other intelligent beings have been encountered.
Then suddenly an isolated star called Mote is discovered. The so-called Moties are welcoming, but they're also harboring a dark problem — one that has haunted them for a million years.
Submitted by Reddit user Iamsock.
"A Canticle for Leibowitz" by Walter M. Miller Jr.
600 years after a nuclear holocaust, a monk from the Order of Saint Leibowitz makes a discovery of the holy relics of the great saint himself that could be the key to mankind's salvation — a fall out shelter and blueprint for an atomic bomb.
The book follows the evolution of humanity through three parts as we emerge from the dark ages, but once again face the precipice of another nuclear war.
Submitted by Reddit user P-Rickles.
"Excession" by Iain M. Banks
Two millennia ago, a black star called the "Excession" mysteriously appeared on the edge of space that was older than the universe, and quickly disappeared.
Now it's back, and it is diplomat Byr Genar-Hofoen's job to discover the secret of the lost sun while his race is at war with a dangerously expansionist alien populace.
Submitted by Reddit user rthrtylr.
"Starship Troopers" by Robert A. Heinlein
"Starship Troopers" tells the story of Juan Rico decides to join earth's marine fighting force to combat alien enemies. The book follows the rigorous training the men go through in the boot camp, and the psychological state of the recruits and their commanders.
One of the original sci-fi greats, "Starship Troopers" went on to inspire many other military science fiction novels, like Joe Haldeman's "The Forever War."
Submitted by Reddit user theformer.
"Do Android Dream of Electric Sheep?" by Philip K. Dick
The inspiration for the movie "Blade Runner," "Do Androids Dream of Electric Sheep?" is set in 2021, after a world war has killed millions of people, driving entire species into extinction. Those who remain build simulacra of past species including horses, birds, cats, sheep ... and humans.
Because the androids are so realistic, it's impossible to tell them apart from real people. But now it's bounty hunter Rich Deckards job to do just that — and then kill them.
Submitted by Reddit user BiohazardBlaze.
"Ringworld" by Larry Niven
"Ringworld" is the story of 200-year-old human Louis Wu as he sets out on an expedition to explore an unknown world with two aliens and his fellow 20-year-old human Teela Brown.
The book follows their adventures on Ringworld, a large, mysterious artifact 600 million miles long rotating around a star, as they attempt to discover its secrets — and then escape.
Submitted by Reddit user UptownDonkey.
"2001: A Space Odyssey" by Arthur C. Clarke
From the author of "Childhood's End" and "Rendezvous with Rama," "2001: A Space Odyssey" follows a scientific mission after a 3 million-year-old enigmatic monolith is found buried on the moon that points towards Saturn.
The best of earth's scientists are sent to investigate with the ultra-advanced HAL 9000 computer. But HAL's programming has been patterned after the human mind, and he is capable of guilt, neurosis ... and even murder.
Submitted by Reddit user Llamalogy.
"The Forever War" by Joe Haldeman
Written by a Vietnam veteran as an allegory of the Vietnam War, "The Forever War" follows reluctant soldier William Mandella as he leaves earth to battle the mysterious alien race, the Taurans.
But because of time dilating during his spaceship travels, he ages 10 years while 700 years pass by on earth. Mandella then returns to a completely different planet that he can no longer recognize.
Submitted by Reddit user spicywith.
"Snow Crash" by Neal Stephenson
Hiro Protagonist may only be a pizza delivery guy in futuristic Los Angeles, but in the "Metaverse" he's a sword-wielding warrior prince.
When a new drug known as "Snow Crash" begins killing off his fellow hackers in the Metaverse, Hiro must team up and find out where the dangerous narcotic is coming from.
Submitted by Reddit user beastduels.
"Neuromancer" by William Gibson
This futuristic crime caper follows Case, a burnt-out hacker and cyber thief whose ability to "jack in" to cyberspace is restored by a miracle cure. He's hired by a mysterious man named Armitage, but as his hacking mission continues he soon finds someone — or something — else is pulling the strings.
"Neuromancer" was the first novel to win the triple crown of sci-fi awards (the Hugo Award, the Nebula Award, and the Philip K. Dick Award) and inspired the "Matrix" series.
Submitted by Reddit user HenryKillinger.
"Hyperion" by Dan Simmons
This Hugo Award-winning novel is the first in a series about seven travelers who set out on a mission to find the mysterious monster Shrike and save mankind from impending doom.
It's rumored if you survive the Shrike, one wish will be granted. With the entire galaxy at war and on the eve of Armageddon, the seven pilgrims are the last hope of humanity.
Submitted by Reddit user oOJohnnyOo.
"Foundation" by Isaac Asimov
"Foundation" is set so far in the future that humans have all but forgotten Earth, and live throughout the galaxy.
All seems well, but scientist Hari Seldon predicts that the Empire is about to collapse and send humanity into a new Dark Age for 30,000 years. He concocts a scheme to save the knowledge of the human race in an encyclopedia, and re-erect the empire over a series of generations.
Submitted by Reddit user TronGod666.
"Ender’s Game" by Orson Scott Card
Andrew "Ender" Wiggin thinks he has been chosen to be trained for combat with computer simulated war games, when in fact he might be the military genius Earth needs to fight off an alien enemy known as "Buggers."
The first book of the series, "Ender's Game" begins when Ender is only six years old, and follows him through his first years of training.
Submitted by Reddit user aliceberrysmith.
"Hitchhiker’s Guide To The Galaxy" by Douglas Adams
In the first book of the series, Arthur Dent is warned by his friend Ford Prefect — a secret researcher for the interstellar travel guide "The Hitchhiker's Guide to the Galaxy" — that Earth is about to be demolished.
The pair escapes on an alien spaceship, and the book follows their bizarre adventures around the universe along with quotes from "The Hitchhiker's Guide" like: "A towel is about the most massively useful thing an interstellar hitchhiker can have."
Submitted by Reddit user saywhat181.
"Dune" by Frank Herbert
No sci-fi list is complete without mention of Herbert's "Dune," which is essentially to science fiction what "Lord of the Rings" is to fantasy.
Herbert is able to create complete histories, politics, religions, and ecological systems of this feudal interstellar society. Set on the desert planet Arrakis, Paul Atreides transforms into a mysterious man known as Muad'Dib as he sets out to avenge the murder of his father, and leads a revolution that earns him the emperor's throne.
Submitted by Reddit user Spanglish_Inquistion.