- Silver Valley (Volume Three)
- Silver World: The Silver Sequence (Book 3)
- Silverdome
- Simak Vol.1 : Hunt on Solar Corona
- Simak Vol.2 : Deadly Games
- Simantov
- Simba The Fireboy and The Aliens of Yttrium
- Simba The Fireboy: Simba Takes on The Giants
- Simmons from Accounting: the Time Traveler
- Simon of Space
- SIMOOM: The Sky's Alight Trilogy - Book 3
- Simulation
- Sin alternativa
- Sin and Error Pining and Other Seasonal Tales from iHero Entertainment
- Sinclair Academy - 01
- Sindbad the Sailor (Read Aloud, Illustrated)
- Singer from the Sea
- Singularidad #3253
- SINGULARIDAD TEMPORAL
- Singularity
- Singularity Deferred
- Singularity One Book Two
- Singularität
- Singularité
- Sinister Paradise
- Sink In Your Claws
- Sinner
- Sinners of Erspia
- Sins of Legion
- Sins of Mars
- Sins Of The Father
- Siobhan Dunmoore: Books 1-3
- Sioras4: Recunoaşterea
- Sioras4: The Recognition
- Sip
- Sir John In Space
- Siren Song
- Sirenor: Endure
- Sirens of Morning Light
- Sirens Of Theta X
- Sirens Of Theta X: The Return Of The Dragons.
- Sirius. In caduta libera
- Sister Blood
- Sister Snow
- Sisterhood of Dune
- Sisters of the Forsaken Stars
- Sisters of the Vast Black
- Sisyphus Shrugged
- Site R Ravenrock
- Six Against the Stars
- Six Days Inside A Mountain
- Six Demon Bag
- Six Lost Souls
- Six Meet Prehistoric Man
- Six Moon Dance
- Six On The Moon
- Six Scifi Stories Volume Four
- Six Scifi Stories Volume One
- Six Scifi Stories Volume Three
- Six Scifi Stories Volume Two
- Six Seconds
- Sixshooter
- Sixth Extinction
- Sixty Days and Counting
- Sjambak
- Skaza na niebie
- Skeen's Leap
- Skeen's Return
- Skeen's Search
- Sketches
- Skies of November
- Skies of Wonder, Skies of Danger
- Skii: Furious Heart
- Skin and Bones
- Skin Deep
- Skin Shifters
- Skin Slickers
- Skinner Builder in 3 Heartbeats
- Skint Idjit
- Skip Thruster, Space Detective
- Skirmish
- Skirmishes: A Diving Novel
- Skirmish
- Skirmishes: A Diving Novel
- Sklaven der Klau
- Sklenený meč
- Skrymers Handske
- Skullcap
- Skulls
- Skulls in the Stars
- SKV -- Smart Killing Virus
- Sky Bound
- Sky Coyote
- Sky Girl and the Superheroic Adventures
- Sky Hunter
- Sky Streak of Terror
- Skyblaze
- Skyburst
- Skye Object 3270a
- Skyfall
- Skyfall: Your Heart Will Fall Too
- Skyjackers: Episode 1: A Proper Nuisance
- Skylark
- SkyLine: The Captain, The Billionaire Boat and The Dragon Crusader
- SkyLine: The Dragon Commander
- Skytrails Part One
- Skyward
- Skywatch
- Slave Empire: Prophecy
- Slave Planet
- Slave Ship: Star Wars (The Bounty Hunter Wars)
- Slave Space
- Slave To The Sands
- Slave to War
- Slavemakers
- Slaves of Hyperion (Star Crusades Uprising, Book 6)
- Slaves of the Dust
- Slaves of the Switchboard of Doom
- Slaves of the Unknown
- Sledgehammer
- Sleeper Cell
- Sleeping Boys