explanation of ancient races that populated the cosmos with similar beings. The notion surfaces in Ursula K. Le Guin's Hainish novels (see The Left Hand of Darkness; The Dispossessed) and was introduced to justify the humanoid aliens of Star Trek (who even intermarry and have children) in the Star Trek: The Next Generation episode "The Chase" (1993).Another common idea is aliens who closely resemble animals. Among the many fictional aliens who resemble Earth's animals, Westfahl lists: Francis Flagg's The Lizard-Men of Buh-Lo (1930) the winged Hawk-Men of the serial Flash Gordon (1936) and its sequels the insect-like alien enemies of Robert A. Heinlein's Starship Troopers and Orson Scott Card's Ender's Game the cat-like aliens of Fritz Leiber's The Wanderer (1964) the "mog" - "half man, half dog" - of the farcical Spaceballs (1987) Westfahl continues, "However, Stanley G. Weinbaum's A Martian Odyssey (1934) encouraged writers to create genuinely unusual aliens, not merely humans or animals in disguise. Olaf Stapledon also populated the universe with disparate aliens, including sentient stars, in Star Maker. Later, Hal Clement, a hard science fiction writer famed for strange but plausible worlds, also developed bizarre aliens in works like Cycle of Fire (1957)." See also Articles related to the phenomenon of extraterrestrials in fiction and popular culture: History of science fiction Alien invasion Parasites in fiction List of fictional extraterrestrials List of films featuring extraterrestrials List of humanoid aliens Articles related to the purported or theorized existence of extraterrestrials: Beliefs in extraterrestrial life Grey alien, frequently reported alien in field of ufology, now with some usage in fiction and popular culture References Further reading Roth, Christopher F., "Ufology as Anthropology: Race, Extraterrestrials, and the Occult." In E.T. Culture: Anthropology in Outerspaces, ed. by Debbora Battaglia. Durham, N.C.: Duke University Press, 2005. Sagan, Carl. 1996. ''The Demon-Haunted World: Science as a Candle in the Dark: chapter 4: "Aliens" External links UFO occupants - grey and reptilian alien pictures ufologie.net - The Filiberto Caponi close encounter of the 3rd kind, 1993 ufocasebook.com - Filiberto Caponi Close Encounter 1993 The Ilkley Moor encounter of the 3rd kind, 1987 UFO Magazine UK and Discussion Forum Jain, A.K - Professor Best Use of Aliens As Metaphor 1950s neologisms Fiction about outer space Science fiction themes