QUOTE(Mind_Freak2012 @ Nov 23 2005, 10:36 AM) [snapback]945734[/snapback]
Yeah, but the greys in Close Encounters, were tall and thin.
No, they weren't.

The only tall alien depicted in CE3K was (what I assume to be) the commander.
As to the term little green men, the following site gives a detailed look at it's origins.
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Electronic searches show that "little green men" was specifically used in reference to science fiction and flying saucers by at least 1951 in the New York Times and 1952 in the Los Angeles Times. The familiarity with which the term was used suggests that these weren't the first instances where it was applied to extraterrestrials. The next example of the New York Times using the term dates from 1955 in a book review of a sci-fi satire called Martians, Go Home. The Martians were obnoxious "little green men" whose appearance was "true to prophecy."
The term also shows up much earlier in rather surprising ways in other contexts. Movie gossip columnist Hedda Hopper used it in 1939 referring to small cast members of the Wizard of Oz, and admonished against drinking on the set. In 1942, the Los Angeles Times used the term in a pictorial on Marines training for jungle combat. In this case, "little green men" referred to camouflaged Japanese soldiers.
Before its more modern application to aliens, little green men was commonly used to describe various supernatural beings in old legends and folklore and in later fairy tales and children's books. Folklore researcher Chris Aubeck noted several examples of the latter in 19th and early 20th century literature. As an example, Rudyard Kipling had a "little green man" in Puck of Pook's Hill from 1906.
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Nowadays most ETs are described as "little grey men". Why is this, I wonder? Anyone have any ideas about this color change?
It just happens to be the color de jure.