You’re right, I can’t offer any proof of Coleridge’s existence. It must have been a dream.
There really was a “Man in the Iron Mask.”
Since Kilroy was mentioned, here’s the Staff Report on the subject: What’s the origin of “Kilroy was here”?
The problem was when you mentioned the movie Xanadu with Olivia Newton-John which despite all attempts to prove otherwise is a real film and a real person 
Well, lay off the opium, then.
:dubious: The odds of getting picked up by a passing spacecraft after being ejected from another one, based on current scientific knowledge, are precisely zero.
I’ve always wondered if Curtis Lowe was a real person. Does anybody know?
How about Wong Fei Hung (sp?)? He was a real person. He was a martial artist and doctor that did some anti-government um…stuff. Hong Kong film industry made over 100 movies about him, so I’m told. Iron Monkey is probably the most recent best one (although it’s about his father mostly). I believe his children were somewhat involved in the film promotions.
The character “Hunter S. Thompson” appearing in the many books by the author Hunter S. Thompson was actually a real person; journalist Hunter S. Thompson, who incidentally authored the books in which the character Hunter S. Thompson appeared and went by the same name.
Somebody already mentioned Imhotep, the real physician and architect who designed the first Pyramid. He later became mythicized into a god of medicine, being identified as Aesclapius by the Greeks.
Edmund Morris and Ronald Reagan are 2 fictional characters that really existed, or so I’ve heard.
As I write this I am sitting at work about 6 blocks west of where the O’Leary barn was. While Mrs. O’Leary did indeed exist and she did have a cow, it seems clear that she didn’t have anything to do with starting the fire. Cite.
The character Dill, in To Kill a Mockingbird, was Harper Lee’s childhood pal Truman Capote.
Bearing in mind that Jeffreys’ most famous appearance in fiction is in Lorna Doone, it’s perhaps worth mentioning that it is sometimes claimed that the Doones were a real family.
Instead of a famous ‘mythical’ person, how about a place ?
Nutbush is real, you murricans will know that, perhaps international dopers may not.
Nutbush may not last much longer though, judging from various photos on a few websites, its still in decline, and there isn’t all that much further to go.
Cisco, what would you say if I told you that I’m actually from a small planet in the vicinity of the star Betelgeuse, and not from Guildford after all?
We would offer a kind-hearted & entirely sympathetic suggestion of Thorazine & Prozac.