Back to the Future was co-written by the director, Robert Zemeckis, and Bob Gale, whose other credits include Back to the Future II, Back to the Future III, Back to the Future… the Ride, Back to the Future the TV series, and Back to the Future the video game.
Okay, so Mr. Gale was never quite able to break out of the Back to the Future mold after penning what would be his crowning achievement. He's worked on a ton of smaller projects—nearly all with his partner in crime, Rob Zemeckis—and has also done a lot of comic book writing for Marvel and DC Comics, but for the most part he has kind of backed away from the limelight.
Gale always had a fascination with comic books and the characters that populated them. In fact, he even created his own comic book when he was just a kid. It was called The Green Vomit. We're not even kidding. We aren't exactly sure how the Vomit's superpowers worked, but we're assuming that Dramamine was basically his Kryptonite.
Gale came up with the idea for BTTF one day when he was wondering whether he and his father might have been friends if he'd known him back when he was his own age. He unfortunately lacked flux capacitor technology…so the next best thing he could do was write about it. And write about it he did.