Star Wars: 14 Crazy Rumours Lucasfilm Started About The Empire Strikes Back In 1980

7. Vader Is Luke's Father (And Other Crazy Suggestions)

Wait, what? As the story of the saga-redefining twist that Darth Vader was Luke's father goes, the reveal was kept so tight you could count the people who knew it on one hand - Irvin Kerschner, George Lucas, Lawrence Kasdan, Mark Hamill and James Earl Jones. The script instead had the equally big "Obi-Wan killed your father" and Hamill was only told moments before shooting. All of this was in the effort to keep the mystery as tight as possible.

And yet Lucasfilm gave it up readily months before release; when discussing the (rumoured) final lightsaber duel between Luke and Vader (allegedly to make up for the pair not having a direct confrontation in Star Wars), there was talk of some final shocker:

More than once we've heard that it turns out that Vader is really Luke's father! Of course, we've also heard, from reliable sources, that Ben Kenobi is really Luke's father, and, from still other sources that Ben killed Luke's father.

Whether Miller intended to give away the twist or if he even knew of it (if he did, then the stories of extreme secrecy at Lucasfilm were exaggerated) is unknown, but this really realigns the contemporary view of how the secret was handled.