R rated sci-fi books

5467 books

Sci-fi books with mature content including explicit sex, graphic violence, or strong language. For adult readers.

21st Century Sub
21st Century Sub
Frank Herbert
R
Love Galaxy
Love Galaxy
Sierra Branham
R
Humans vs. Aliens
Humans vs. Aliens
T. Jackson King
R
Machine Mage
Machine Mage
Josh Kendig;Dan Raxor
R
The Door to December
The Door to December
Richard Paige
R
Hellflower
Hellflower
Eluki bes Shahar
R
Star City
Star City
Tully Zetford
R
Signal Lost: A Sci-Fi Alien Romance
Signal Lost: A Sci-Fi Alien Romance
Onyx Sullivan
R
Ruby: Alien Hunting Grounds Book 6
Ruby: Alien Hunting Grounds Book 6
Kyla Breene
R
Tom Swift and His Television Detector, or, Trailing the Secret Plotters
Tom Swift and His Television Detector, or, Trailing the Secret Plotters
Victor Appleton
R
Tom Swift and His Flying Lab
Tom Swift and His Flying Lab
Victor Appleton, II
R
The Alien Probe
The Alien Probe
Victor Appleton
R
Gateway to Doom
Gateway to Doom
Victor Appleton
R
Mutant Beach
Mutant Beach
Victor Appleton
R
Fire Biker
Fire Biker
Victor Appleton
R
Beanstalk
Beanstalk
John Rackham
R
The Wonder
The Wonder
J. D. Beresford
R
The Arena: A Military Sci-Fi Adventure
The Arena: A Military Sci-Fi Adventure
Craig Martelle
R
Ignore All Previous Instructions
Ignore All Previous Instructions
Ada Hoffmann
R
Space Men
Space Men
David Shaw
R
The Professor's Experiment
The Professor's Experiment
Margaret Wolfe Hungerford
R
Death's Messenger
Death's Messenger
Alex Stewart
R
Every Inch a King
Every Inch a King
Harry Turtledove
R
Hero Chimera: A Progression Fantasy
Hero Chimera: A Progression Fantasy
Zachary Holzgen
R
Rocket Racers
Rocket Racers
Victor Appleton
R
Star Marines
Star Marines
Ian Douglas
R
Arrival
Arrival
Joshua James
R
Raising Abel
Raising Abel
W. Michael Gear; Kathleen O'Neal Gear
R
Ravenor Rogue
Ravenor Rogue
Dan Abnett
R
Pilot's Paradox
Pilot's Paradox
Richard Tongue
R