Novel in which alien (Martian?) is trapped on Earth in prehistory
26358
Book about ancient Martian astronauts being the root of modern humanity and time travel
116839
Novel about alien species made of gas rings?
122993
Short story, possibly a Bradbury one: adventurers find a weapon cache of dead Martian civilization, and unleash a blob
93979
Help Identifying a Sci-Fi Book: Humans transported to alien world and given tasks to escape
35707
SF novel about one-way scientific expedition to inhabited planet, where telepathic aliens "talk" sort of ++like this++ and ~*~this~*~
126418
Story about encounter with hostile aliens
37150
Sci-fi novella where colonists begin to de-evolve - Mankind has reached limits of its evolutionary cycle
16594
Earth occupation/invasion book I read in the 90s
87095
Sci-fi novel involving living forever through teleporter copies
155220
Short story about humans as beasts of burden for another race, read about 30 years ago
73275
Pre-1972 sci-fi short story or novel: alien(?) tunnel where people try new moves and get destroyed if they're not the correct ones
5178
Novel with an alien rabbit invasion
154725
Looking for identification of SF story where humans are the "ancient evil"
101007
Short story from many years ago: the ancient, brilliant, cruel race was Earthlings
94172
Science Fiction story about humans escaping earth's destruction
11587
Need title of early sci-fi Mars movie
105120
Older fantasy novel with alternate world and musical themes