Attila the Hun:

One of the most notorious villains in history, Attila's army had conquered
all of Asia by 450 AD--from Mongolia to the edge of the Russian Empire--by
destroying villages and pillaging the countryside.

How he died: He got a nosebleed on his wedding night

In 453 AD, Attila married a young girl named Ildico. Despite his 
reputation for ferocity on the battlefield, he tended to eat and drink 
lightly during large banquets. On his wedding night, however, he really 
cut loose, gorging himself on food and drink. Sometime during the night he 
suffered a nosebleed, but was too drunk to notice. He drowned in his own 
blood and was found dead the next morning.