The Seafarer -- Lockhart telling Sharky what hell is like, as the moon and stars slowly light up above the set, and then the moment when he pauses then says 'You would have loved heaven, Sharky'
Troilus and Cressida (at the RSC, with Philip Quast) -- when Achilles came in carrying Patroclus' body, bathed in red light, and in the quietest, deadliest voice, vowed his revenge on the Trojans
Angels in America -- Ethel with her hand on Louis' shoulder, helping him thru the kadisch when Roy dies
War Horse -- the tank scene, and when the 'dying' wispy horses come onto the stage, pulling the medical wagon
Faith Healer -- the end of Frank's last monologue, when he steps out to the front of the stage and says 'At long last I was renouncing chance'
Black Watch -- the scene with each soldier getting his letter and reading it, and then 'signing' what it said
You don't go to the dragon without a present - Mark Rylance