"That's all very well," said Balzac, "but let's get back to reality: to whom are we going to marry Eugénie Grandet?" Eugénie was, of course, fictional, but Balzac wouldn't be the first or last person to mistake a fictional character for a real. Aside from the countless literary personifications, however, there is a class of--dare I say "cultural constructs"?--imaginary beings who take on a life of their own. I suggest:
Ignoto, sometimes plagiarized for use in these pages. Thanks to Larry for Spelvin and Peter for Shrdlu. John would add Hadley v. Baxendale, who starred in a famous porn film (btw I once knew a man named Price v. Neal). Joel suggests the gang of ruffians in the credits to Garrison Keillor or CarTalk--Erasmus B. Dragon, Picov Andropov, that kind of stuff. But don't they verge on literature? With the same reservation, I rejected Miss American Pie.
Are there others?