Books about Human-alien encounters -- Fiction (sorted alphabetically)
- Cargo to Callisto Jerome Bixby
- Car Pool Rosel George Brown
- Catspaw George O. Smith
- Child of the Sun Leigh Brackett
- Children of the Chronotron S. J. Byrne
- Cinderella Story Allen Kim Lang
- Citadel of the Green Death Robert Emmett McDowell
- Citadel of the Star Lords Edmond Hamilton
- City of the Living Flame Henry Hasse
- Clean Break Roger D. Aycock
- Collector's Item Evelyn E. Smith
- Colossus of Chaos Nelson S. Bond
- colour out of space H. P. Lovecraft
- Combatman John Massie Davis
- Come Into My Brain! Robert Silverberg
- Come into my parlor Charles E. Fritch
- Coming of the Gods Chester Whitehorn
- Common Denominator John D. MacDonald
- Communication Charles L. Fontenay
- Con-Fen James R. Adams
- Conquistadors Come Mary Elizabeth Counselman
- Contact Point Jack Sharkey
- Contamination Crew Alan Edward Nourse
- Corpus earthling Louis Charbonneau
- Cosmic Bluff Mack Reynolds