Human-alien encounters Extraterrestrial beings 28 Life on other planets 18 Interplanetary voyages 16 Interstellar travel 9 Unidentified flying objects 9 Alien abduction 7 rhagor ... Odo (Fictitious character) 7 Sisko, Benjamin (Fictitious character) 7 Space stations 7 Space warfare 7 Exploration 6 Imaginary wars and battles 6 History and criticism 5 Conspiracies 4 History 4 Millennialism 4 Extraterrestrial anthropology 3 Friendship 3 Man-woman relationships 3 Martians 3 Science fiction 3 Science fiction films 3 Sightings and encounters 3 Social aspects 3 Social change 3 Space flight 3 Time travel 3 Artificial intelligence 2 Civilization, Medieval 2 llai ...