7. Tauriel
Not so much a moment as an actual character, but the inclusion of this original creation by Peter Jackson was a bold move which really ended up paying off. The Hobbit is a story seriously lacking in interesting and powerful female characters, so adding in a kick-ass elf like Tauriel helped The Hobbit: The Desolation of Smaug in a lot of ways.
Evangeline Lilly stole the show in the scenes she was in as she fought alongside Legolas and helped to add an interesting subplot to the movie as the relationship between her and Kili developed (how that plays out in The Battle of the Five Armies should be very interesting to see). Some fans objected initially, but they were quickly silenced upon the movie’s release. Jackson knows what he’s doing.
