http://www.bay12games.com/forum/index.php?topic=27060.0
I believe that one takes the cake. Even if he didn't technically die.
Curse you Kurisukun, you stole my most horrible death. I was going to post it. =P
For my second most horrific death I had a dwarven recruit that came fresh from the mines. I figured he could do some military duty, and soon enough he got his chance. An ambush came before he became a wrestler, and I sent him out with the rest of the platoon. When the skirmish came to an end Poor Urist had lost an arm and an eye. To be certain I wasn't going to let him become useless, so after some recovery time he was back up and ready to go. I set him to be a marksdwarf. He became competent, and was put on the military rotation.
Another ambush, this was his time to shine. He rushed right out with the rest of the military, All of them prepared to fight. 5 seconds later, one third of the military decided that it was a good time to get something to drink. The remaining two thirds were then met with the incoming bolts of goblin crossbowmen. Several of my dwarves fell then and there. While Urist fired back. He had taken a few hits as well, mostly to the legs which were now crippled. Again, by the end he had lost his other eye and an ear, along with his left leg.
Once the military might of our fortress had failed it was up to the civilians to carry out plan B. A row of 8 masterwork ballistas and 8 Legendary operators. I do feel a tad bit of guilt firing on a battlefield where there are still some surviving soldiers (The drinkers had run back out to the battlefield by this point, and were being thoroughly thwarted), but I think the ends justified the means.
Urist managed to survive the onslaught due to a lucky fall (between the ballista's firing area). He was retrived and treated for his wounds. He never fully recovered from his wounds before the ultimate fall of the fortress by an accidental loosing of a caged dragon inside the fortress. He burned to death in his bed. A death that was a long time coming.
I almost nicked him 'Lucky' but had second thoughts, as I felt it too cruel to call his survival 'luck'.