Herman Wouk once complained that one of his novels got adopted by Hollywood by changing a country man into an urban woman. I don’t recall which book or movie he was talking about, but it’s par for the course.
Most of the movies listed here really don’t have much of a change at all. You want Different, try these:
The Screaming Mimi and The Bird with the Crystal PLumage, both ostensibly based on Fredric Brown’s "The Screaming Mimi
The Day the Earth Stood Still, based on “Farewell to the Master” (And a good change it was)
Who Framed Roger Rabbiot, based on “Who Censored Roger Rabbit?”, another good change
The Terrornauts based on Murray Leinsters “The Wailing Asteroid”
Starship Troopers – no more need be said
I, Robot – ditto
The Osterman Weekens, based, supposedly, on the Robert Ludlum book of the same name
Both versions of The Bourne Identity, for that matter.
Ice Station Zebra by Alistair Maclean
The James Bond novels-to-movies Casino Royale (the 1967 version), Doctor No, You Only Live Twice, Live and Let Die, Moonraker, The Spy Who Loved Me (arguably the winner in this derby), The Man with the Golden Gun, Octopussy, and The Living Daylights
This Island Earth, to my chagrin, given my name
Invasion of the Saucermen (Based on Wellman’s “The Space Frame”), Total Recall (based on Philip K. Dick’s “We Can Remember It For You Wholesale”), and Mimic (based on Donald Wollheim’s “Mimic”) all actually covered the original story, but then had so much time left on their hands that 70% or more of each has nothing to do with the original idea.
Philip K. Dick ought to get his own category. Compare the book or story versions he wrote with **Bladerunner, Paycheck, Screamers, Total Recall, ** or Minority Report with his original. About the only time they were faithful was A Scanner Darkly.
I’d like to see Frddric Brown done properly one of these days – either his science fiction, or his fantasy, or his detective fiction. Besides what’s listed above, we have vastly changed versions of Arena, Martian Go Home, and Knock 3-1-2.
I’d like to se Robert Sheckley’s stuff done properly, too. Freejack had virtually nothing to do with “Immortality, Inc.” and The Tenth Victiom little to do with “The Seventh Victim”. Disney’s Condorman wasn’t exactly his “The Game of X”… I’m curious to see how well “Masters of Science Fiction” did with his “Watchbird”. It wasn’t broadcast, but I noticed over the weekend that it’s now out on the DVD (as Exapno had predicted). I’m almost curious enough to pick it up, except that most of the rest of the series was awful. Sheckley has to be the most ripped-off author. I thought that Total Recall, The Running Man , and other films lifted ideas from him without attribution.