COMIC LEGEND: Walter Simonson and David Michelinie accidentally came up with a major plot point for Return of the Jedi before the film came out.
Reader Ed wrote in awhile back to ask:
Here’s a suggestion - in the original Marvel Comics run of Star Wars, there was a story (by David Michelinie and Walt Simonson?) where the Empire made a battle station called The Tarkin. This was between Empire Strikes Back and Return of the Jedi. I heard somewhere that the original storyline was to build a second Death Star, but when Lucasfilm saw the script they nixed it because it was too similar to RotJ. I’d love to know if there’s any truth to that!
That's pretty much EXACTLY what happened, Ed.
Here's Walter Simonson himself explaining it from Modern Masters Volume 8:
We began finding out what would be in the third movie, accidentally. We didn't do it deliberately. David's first story after the second movie: the Empire's building a new Death Star. Lucasfilm said: 'Sorry, you can't do that.' Why not? 'We can't tell you.' So, we said okay, how about if we do a giant cannon floating in space, with no circular shell? 'Okay, fine, no problem.' So we called it the Tarkin, wrote exactly the same story with the same gizmo, and nobody cared.
The story appeared in Star Wars #51-52.
And as we noted on the previous legend, Lucasfilm paid a lot of attention to the Marvel Comics.
Thanks to Ed for the question and Walter Simonson and Modern Masters for the info (thanks to Matt P. for identifying where the quote came from!).