Ufos at the sky --- Image by © Sagel & Kranefeld/Corbis
Invasion --- Image by © 68/Colin Anderson/Ocean/Corbis
23 Aug 2002 --- Green Alien Face --- Image by © Envision/Corbis
Extraterrestrial in the Mist --- Image by © Mike Agliolo/Corbis
Extraterrestrial --- Image by © Mike Agliolo/Corbis
Boy Wearing Alien Mask --- Image by © Rainer Holz/Corbis
Pacific Islander woman wearing futuristic combat gear --- Image by © Colin Anderson/Blend Images/Corbis
06 Dec 2009 --- A thin veil of gaseous material surrounding the blue-white star Vega is seen here as a hazy sunrise on a small moonlet in orbit around the cloudy planet. Vega itself is still below the horizon. --- Image by © Stocktrek Images/Corbis
August 24, 2010 --- Alien, computer artwork. --- Image by © VICTOR HABBICK VISIONS/Science Photo Library/Corbis
A man out in the foggy wilderness is being abducted by a U.F.O. with a bright beam of light. --- Image by © C.J. Burton/Corbis
20th century --- Magazine Cover with Robot War Machines by Blade Gallentine --- Image by © Forrest J. Ackerman Collection/CORBIS
1985 --- Montage of Science Fiction Scenes with Portrait of Illustrator Frank R. Paul by Anton Brzezinski --- Image by © Forrest J. Ackerman Collection/CORBIS
1985 --- Painting of Science Fiction City Battle by Anton Brzezinski --- Image by © Forrest J. Ackerman Collection/CORBIS
1929 --- Original caption: Cover of the 1929 science fiction magazine "Amazing Stories". Three war robots attacking the citizens of Earth are the featured illustrations of Frank R. Paul that describe the events in H.G. Wells' story, "War of the Worlds". SEE NOTE FOR DIGITAL ACCESS --- Image by © Corbis
UFO incident in the desert --- Image by © Richard Morrell/CORBIS
26 Jan 1989 --- This aerial photograph of a Martian butte, taken by Viking in 1976, was seized upon by the paranormal community as evidence of civilization on Mars, even though such illusions are common in nature. --- Image by © 1989 Roger Ressmeyer/NASA/CORBIS
Ufos above the city --- Image by © Claudius/Corbis
Alien --- Image by © Gregor Schuster/Corbis
Man in Alien Costume --- Image by © Rainer Holz/Corbis
Space Alien --- Image by © Mike Agliolo/Corbis
Nevada, USA --- Aluminum alien statue near Extra Terrestrial Highway in Nevada --- Image by © Momatiuk - Eastcott/Corbis
Alien making contact --- Image by © Colin Anderson/Blend Images/Corbis
Red robot attacking with beams from eyes --- Image by © Ikon Images/Corbis
Inflatable alien with Welcome to Roswell sign in background --- Image by © Vstock LLC/Tetra Images/Corbis
Alien abduction. Alien beings examine a human woman on their spaceship. posed by models 1998 --- Image by © David Levenson/Corbis
15 Nov 2012 --- A pair of P-51 Mustang Fighter planes blowing up a crashed alien vehicle and it's robotic crew member, during Earth's ongoing secret war with this robotic enemy race. --- Image by © Mark Stevenson/Stocktrek Images/Corbis
20th century --- Painting of a Science Fiction Scene with Robots and Spacemen by Anton Brzezinski --- Image by © Forrest J. Ackerman Collection/CORBIS
Alien --- Image by © Randy Faris/CORBIS
Cow Abducted by Aliens --- Image by © Clark Dunbar/Corbis
ca. 1951 --- Gort standing by his spacecraft in a scene from The Day the Earth Stood Still. --- Image by © John Springer Collection/CORBIS
ca. 2002, USA --- Extraterrestrial with American Flag Painted on Forehead --- Image by © Bob Rowan/Progressive Image/Corbis