Books about Human-alien encounters -- Fiction (sorted alphabetically)
- Stamped Caution Raymond Z. Gallun
- Star Beast Damon Knight
- Star-Crossed Lover William W. Stuart
- Star of Panadur Henry Hasse and Albert dePina
- Steel Giants of Chaos James R. Adams
- Stellar Vengeance Frank Freeman
- Strange Exodus Robert Abernathy
- Stranger Gordon R. Dickson
- Student Body F. L. Wallace
- Summer Guests James H. Schmitz
- Sunfire! Edmond Hamilton
- Survival Type Jesse F. Bone
- Sweeper of Loray Robert Sheckley
- Sweet Tooth Robert F. Young
- Sword Frank Quattrocchi
- Sword of Johnny Damokles Hugh Frazier Parker
- Task Mission Fox B. Holden
- Task of Kayin Joseph Samachson
- Terror Out of Space Leigh Brackett
- Terror Out of Space Dwight V. Swain
- Test Colony Winston K. Marks
- The Vilbar Party Evelyn E. Smith
- Thing in the Truck Stephen Marlowe
- Thing of Venus Wilbur S. Peacock
- Third Little Green Man Damon Knight