- Significance: a Science Fiction Short Story
- Signora morte
- Sileise Raided
- Silence Ends
- Silence in Solitude: Book II of the Roads of Heaven
- Silent Autumn
- Silent Dances (StarBridge #2)
- Silent Honor
- Silent Invasion
- Silent Lies
- Silent Manifest
- Silent Order: Ark Hand
- Silent Order: Axiom Hand
- Silent Order: Eclipse Hand
- Silent Order: Fire Hand
- Silent Order: Image Hand
- Silent Order: Iron Hand
- Silent Order: Master Hand
- Silent Order: Omnibus One
- Silent Order: Royal Hand
- Silent Order: Wasp Hand
- Silent Order: Wraith Hand
- Silent Rising
- Silent Songs (StarBridge #5)
- Silent Star
- Silent Sun
- Silent Twin
- Silent Wave
- Silex-M
- Silicon Minds of Mars
- Silicon Moon & Other Stories
- Silicon Strike
- Silk & Steel
- Silk and Sharp Edges
- Silly Alien Space War Stories for Bigger Kids
- Silly Alien Stories for Bigger Kids
- Silly Alien Time Travel Stories for Really Big Kids
- Silly Daddy in Space: A Family Comic of Hope and Hyperspace
- Silvapithecus Americanus: The Discovery of a New Species
- Silver
- Silver Cane Chronicles
- Silver City: The Silver Sequence (Book 2)
- Silver Dagger
- Silver Dreamers
- Silver Hands
- Silver Valley (Volume One)
- Silver Valley (Volume Three)
- Silver Valley (Volume Two)
- Silver Valley: The Complete Collection
- Silver World: The Silver Sequence (Book 3)
- Silverdome
- Silvia-Duett - Folge 15
- 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
- Simbiosys: Ultimate Cyber Attack
- Simmons from Accounting: the Time Traveler
- Simon of Space
- SIMOOM: The Sky's Alight Trilogy - Book 3
- Simple Things
- Simran's Diary
- Simulation
- Simultaneous Times
- Sin alternativa
- Sin and Error Pining and Other Seasonal Tales from iHero Entertainment
- SIN NOMBRE -NO NAME-
- SIN NOMBRE -NO NAME- (VOLUMEN III)
- Sinais (Comandante Serralves)
- Sincerely Yours, Lucifer
- Sinclair Academy - 01
- Sindbad the Sailor (Read Aloud, Illustrated)
- Sine Die
- Singer from the Sea
- Singular Irregularity - Time Travel Gone Terribly Wrong
- Singularidad #3253
- SINGULARIDAD TEMPORAL
- Singularity Deferred
- Singularity One Book Four Green the Unstoppable March of Technological Progress
- Singularity One Book Two
- Singularity Sky
- Singularität
- Singularité
- Singurătatea singularității
- 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 Arthur Conan Doyle's Collection [ 29 books ]
- Sir John In Space
- Siren
- Siren Song
- Sirenor: Endure
- Sirens and Other Daemon Lovers
- Sirens of Morning Light
- Sirens Of Theta X
- Sirens Of Theta X: The Return Of The Dragons.
- Sirius. In caduta libera
- Sistema Stellare Midway: La flotta contro l’invasione
- Sister Blood
- Sister Snow
- Sisters of the Forsaken Stars
- Sisters of The Revolution
- Sisters of the Vast Black
- Sisters of the Wild Sage: A Weird Western Collection
- Sisyphus Shrugged
- Sit-In At The Alamo
- Site R Ravenrock
- Six Against the Stars
- Six and Fifty-Four
- Six Days Inside A Mountain
- Six Degrees of Sky
- Six Demon Bag
- Six Frightened Men and five more stories
- Six Lost Souls
- Six Meet Prehistoric Man
- Six Months, Three Days, Five Others
- Six Moon Dance