Star Wars is no less a dumb popcorn movie than Shrek. I don't know how some people think the original trilogy is high cinema. They're well-made movies and work great for what they are, don't get me wrong. But there's certainly no cause for a Star Wars fan to feel intellectually superior to a Shrek fan.
I knew there was a Jacob in Twilight but I didn't know his last name, so I didn't think of that series when I saw the name... somehow I was stuck thinking about the movie "Meet Joe Black", which I also haven't seen. If I'd let myself think ablut it an extra minute instead of clicking the "giving up" button, I'd have probably thought of it though. Luna's dad, on the other hand, never.
As is fairly typical I had no idea about the Hunger Game or Harry Potter clues, but I got the Harry Potter one accidentally when I started typing in "Xenophon"