Oh God, so many...
Fellowship of the Ring:
- The fight in Balin's Tomb
- The collapsing stairs just after that
- Boromir's last stand and death
Two Towers:
- Gandalf fighting the Balrog in midair as they freefall down a chasm into an underground lake
- The Ents destroying Isengard
Return of the King:
- Faramir's suicidal ride to take Osgiliath while his father calmly eats lunch
- The Mumak (giant elephants) showing up when the battle seemed to be won, and decimating the Rohirrim
- "I can't carry it for you... but I can carry you!"
The Hobbit Part 1:
- The dragon attack. Such a great sense of power and danger.