Breakfast at Tiffany’s, the movie, is loosely based off a Truman Capote short -story of the same name, which is itself loosely based off of a brief period in Truman’s life. IRL, “Holly GoLightly” was nowhere near as naive as the Audrey Hepburn character: She was a hooker not just a party-girl; was well-aware what “Sallie Tomatoe’s” cryptic messages were all about (“A blizzard of ‘snow’ to hit New Orleans??”); and did skip town for South America in the end. George Peppard’s character, being based off of Capote himself, didn’t fall in love with Holly, and didn’t have a married socialite keeping him.
Truman also said something about Holly being modeled after his mother.
I, too, have heard this one; it was rumored through town shortly beforehand that one of the buyers was a fellow who intended to turn Ed Gein’s house into a tourist attraction and “Murder Museum.”
The locals apparently didn’t think this was such a hot idea, and the house went up in flames. The cops investigated, but no suspects were arrested, and the case remains unsolved.
Ed Gein’s house, however, was in … Wisconsin, IIRC.
The “Texas Chainsaw Massacre” house I saw as a kid is near Round Rock, Texas, north of Austin. Never been to Wisconsin, although I hear the scenery’s pretty.
Did I read through the thread too fast, or has no one mentioned The Rose, with Bette Midler, which I’m told was a thinly fictionalized biopic of Janis “The Pearl” Joplin?
Well, in science fiction, the ultimate roman a clef was Ben Bova’s The Starcrossed. It’s really about the production of the TV series, The Starlost, where Bova was a technical advisor. Bova himself appears in the book, and the series’ creator, Harlan Ellison, shows up at “Ron Gabriel.” It’s a humorous exaggeration of what actually happened, with a few science fictional elements thrown in.
Going far back, King Lear is evidently based on an actual event: a rich merchant leaving his money to his children, and them turning on him.
Citizen Kane, of course, was inspired by the life of W.R. Hearst.
And there’s also The Greek Tycoon. Of course, all parallels to real events in the film are purely coincidental. 
James Joyce’s writings were based on his experiences, and John Houston’s last film The Dead was based on Joyce’s short story of the same name, and it was based on events which happened when Joyce and his wife were visiting relatives at Christmas.
That reminds me…
Ray Bradbury wrote a story based on his experiences working with Huston on Moby Dick. “Green Shadows, White Whale”, apparently, checking IMDB’s trivia for the movie.
Going waaaay back, Melville’s “Moby Dick” was loosely based on the experiences of the crew of the Essex, a whaling ship wrecked by an angry sperm whale in the Pacific.
The movie “My Favorite Year” and the sitcom “The Dick Van Dyke Show” are both loosely based on life behind the scenes of Sid Caesar’s “Your Show of Shows.” Mel Brooks (who produced “My Favorite Year”) and Carl Reiner (creator of “The Dick Van Dyke Show”) were both comedy writers for “Your Show of Shows,” and both tried to show what it was like writing sketches for a temperamental (often maniacal) star.
It was quite newsworthy over here; I remember it being in the news for months. The company that lost them tried to play it off as a suicide.
One of the reasons that it made the news, btw, is that strandings are very rare. I used to dive and I’ve got friends who dive frequenty and no-one’s even got friend-of-friend urban legend stories about being left behind.
The 1989 James Woods/Robert Downey Jr movie True Believers is based on an investigation by philosophy professor turned PI, Josiah Thompson which is outlined in his book Gumshoe. The movie makes no reference to this.
I’d never heard that – at any rate, Lear (or Leir as it’s usually spelled in non-Shakespearean sources) is a figure from British mythic history; his story appears in Geoffrey of Monmouth’s History of the Kings of Britain, and much later on in Spenser’s Faerie Queene; Shakespeare’s immediate source, though, was an anonymous play called The True Chronicle Historie of King Leir, which was printed around 1605. Of course, he makes a few changes to the story: his version is the only one where Cordelia dies at the end. (In most versions of the tale, Lear is restored to the throne, reigns for a few more years, and then she succeeds him, but gets deposed by her nephews and ends up committing suicide.) I believe Lear’s madness is also Shakespeare’s invention.
Generally, Shakespeare took his plots either from established literary sources or from history (which isn’t quite what the OP is looking for). Shakespeare’s use of current events doesn’t tend to express itself in plots, but in themes, allusions, and choices of subject matter – a famous example would be the allusions to the Gunpowder Plot in Macbeth (which was, itself, a Scottish play for a Scottish king; indeed, the character of Banquo was supposed to have been an ancestor of the Stuarts, and there’s a nod to that in the play, although modern historians tend to think he probably wasn’t a real person at all).
Having read Ellison’s account of what happened with that, now I REALLY wanna read Bova’s version…
Perhaps I am wrong, but I seem to remember hearing somewhere that the producers originally got the Onassis family’s permission for a biopic of Aristotle Onassis… whereupon, after shooting had begun, some sort of conflict arose… and the Onassis family rescinded their permissions…
…at which point, the producers simply relooped the dialogue to change the actors’ names, and went ahead with the original script, under a new title. Wound up being kind of a bad movie, anyway, I’m told.