This wasn't a PC death, but it was so epic I'm going to put it here anyway.
Name of NPC: Longtooth
Class/Level: Male juvenile red dragon
Adventure: Fortress of the Stone Giants
When Longtooth made his appearance, he naturally noticed the bells clanging, and decided to deviate from his scripted plan of attack and assault the cathedral bell tower first. He flew towards it, flaming and roasting the bard pretty well; he ended his turn in mid-air with the bell tower at the edge of his breath weapon's reach.
The bard baled out of the far side of the tower using Feather Fall -- and then the party's arcane trickster vaulted onto her hippogriff, used its motion to get into range of the dragon from behind it, and cast: Glitterdust.
"Okay, fine," I thought. "So we'll have a shiny red dragon."
Then he rolled a nat 1 on his Will save to avoid blindness.
Blinded, confused, Longtooth kept flying in the same direction he had been, and crashed straight through the bell tower. It crumbled around him with a clangor of falling bells. On the far side he failed a Fly check to remain aloft, fell, and plowed a furrow in the cathedral grounds. The 6d6 of falling damage didn't kill him; nor did the extra 1d6 for debris raining down on him. He even survived two hits from the bard's holy flaming shortbow (Batman!).
When the arcane trickster flew her hippogriff in and hit him with an acid arrow, he would have been fine too -- if he'd been able to see. But he was still blind, flat-footed, and the sneak attack dice did for him.
So in the end, really, it was Glitterdust that killed him. The bard and the arcane trickster high-fived each other and later had leather hot-pants made out of his skin.