Books about Human-alien encounters -- Fiction (sorted alphabetically)
- Riya's Foundling Algis Budrys
- Rockabye, Grady David Mason
- rote Stern: Ein utopischer Roman (German) A. Bogdanov
- Rough Beast Roger D. Aycock
- Round-Up Time Chester Cohen
- Routine for a Hornet Don Berry
- Rx Alan Edward Nourse
- Satellite of Death Randall Garrett
- Satisfaction Guaranteed Joy Leache
- Savage Galahad Bryce Walton
- Scandalized Martians Arnold Marmor
- Scapegoat Richard Maples
- Second landing Murray Leinster
- Secret of the Martians Paul W. Fairman
- Sentimentalists Murray Leinster
- Serpent River Don Wilcox
- Shadrach" Nelson S. Bond
- Shock Troop Richard Bolton
- Short Snorter Charles Einstein
- Sidewinders From Sirius Fox B. Holden
- Sinister Invasion Edmond Hamilton
- Skit-tree planet Murray Leinster
- sky was full of ships Theodore Sturgeon
- Slaughter on Dornell IV Randall Garrett and Robert Silverberg
- small bears Gene L. Henderson