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It's been ten years since the Harry Potter saga delivered one of its most pivotal sequels. "Harry Potter and the Half-Blood Prince" pushed this beloved fantasy saga in a darker direction, complete with a tragic death and new insight into the origins of the wizarding world's greatest villain. Celebrate this milestone by learning more about the making of the sixth Potter movie.

1. "The Half-Blood Prince" is the third-longest movie in the series, falling behind only "Harry Potter and the Chamber of Secrets" and "Harry Potter and the Goblet of Fire."

2. The actor who plays the 11-year-old version of Tom Riddle, Hero Fiennes Tiffin, is the nephew of Voldemort actor Ralph Fiennes.

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3. Though roughly 7,000 girls auditioned for the role of Lavender Brown, Jessie Cave was cast despite not attending these auditions. Fortunately for her, she had a recommendation straight from Emma Watson.

4. This is the first film in the series not to feature any Defense Against the Dark Arts classroom scenes, despite the fact that Professor Snape is revealed to have taken over the class early in the film.

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5. Director David Yates said the film's color and lighting were heavily inspired by the work of Dutch painter Rembrandt. Fittingly, this is the only film in the series to be nominated for the Best Cinematography Oscar.

6. While Yates has directed every "Harry Potter" and "Fantastic Beasts" movie since "Harry Potter and the Order of the Phoenix," WB almost went with a different director for "The Half-Blood Prince." They approached Terry Gilliam, but Gilliam refused, having been passed over to direct "Harry Potter and the Sorcerer's Stone" years before.

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7.Kevin McKidd was approached to play werewolf villain Fenrir Greyback, but had to decline due to his other commitments. McKidd has since said he doesn't regret turning down the part, as it would have terrified his children.

8.Bill Nighy was cast as Minister for Magic Rufus Scrimgeour in "The Half-Blood Prince," but after his scene was cut, Nighy instead made his series debut in "Harry Potter and the Deathly Hallows: Part 1."

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9. The set used for Professor Slughorn's office is a modified version of the same one used for the Trophy Room in "The Goblet of Fire" and the Room of Requirement in "The Order of the Phoenix."

10. Actor Alan Rickman admitted to feeling a perverse sense of glee over Snape's role in Dumbledore's death scene, comparing it to the climax of "Die Hard" and pointing out how his character got to be on the opposite end of a battle involving one character falling to their death.

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11. Narcissa Malfoy actress Helen McCrory was originally cast as Bellatrix Lestrange in "The Order of the Phoenix," but left the project after becoming pregnant.