A long time ago, in a galaxy far, far away… you know the rest. Thanks to Ahsoka, we might actually have an in-universe answer to the question no one thought to ask: who did write those Star Wars opening crawls? (Other than the movie’s writers, clever clogs).
In Ahsoka episode 6, the millennia-old droid Huyang not only reveals the extent of his knowledge, he also tips his hand to his storytelling style. He begins his three-part "History of the Galaxy" tale to Ahsoka by saying, "A long time ago, in a galaxy far, far away."
I – and others – independently arrived at the same conclusion: Huyang is the originator of all of those opening crawls that outline the premise of each mainline movie. The headcanon goes further, with it being possible that Huyang is