[Aragorn and co. leaving camp on horseback]
Soldier: Why does he leave on the eve of battle?
Gamling: He leaves because there is no hope.
Theoden: He leaves because he must.
Gamling: Too few have come. We cannot defeat the armies of Mordor.
Theoden: No. We cannot. But we will meet them in battle nonetheless.
Gandalf: If the beacons of Gondor are lit, Rohan must be ready for war.
Theoden: Tell me, why should we ride to the aid of those who did not come to ours? What do we owe Gondor?
Aragorn: The Beacons of Minas Tirith! The Beacons are lit! Gondor calls for aid.
Theoden: And Rohan will answer!
[Eowyn hands Aragorn a goblet, he drinks and moves away]
Theoden: [to Eowyn] I am happy for you. He is an honorable man.
Eowyn: You are both honorable men.
Theoden: It was not Theoden of Rohan who led our people to victory.
Theoden: Tonight we remember those who gave their blood to defend this country. Hail the victorious dead.
All: Hail!
Theoden: Eomer. Take your Èored down the left flank. Gamling, follow the King's banner down the center. Grimbold, take your company right, after you pass the wall. Forth, and fear no darkness! Arise! Arise, Riders of Theoden! Spears shall be shaken, shields shall be splintered! A sword day... a red day... ere the sun rises!
[the King rides past his men, hitting their spears with his sword as he goes]
Theoden: Ride now!... Ride now!... Ride! Ride to ruin and the world's ending!
[He stops and faces Sauron's army]
Theoden: Death!
Rohirrim: [echoing] Death!
Theoden: Death!
Rohirrim: [echoing] Death!
Theoden: DEATH!
Eowyn,
Merry: Death!
Theoden: Forth, Eorlingas!
Theoden: I have left instruction. The people are to follow your rule in my stead. Take up my seat in the Golden Hall. Long may you defend Edoras if the battle goes ill.
Eowyn: What other duty would you have me do?
Theoden: Duty? No... I would have you smile again, not grieve for those whose time has come. You shall live to see these days renewed. No more despair.
Theoden: I know your face... Eowyn. My eyes darken.
Eowyn: No. No. I'm going to save you.
Theoden: You already did... Eowyn. My body is broken. You have to let me go. I go to my fathers, in whose mighty company I shall not now feel ashamed. Eowyn...
[dies]
Or just basically literally every one of Theoden's lines...