Emperor Yang of Sui

He completed the canal system that still links the Yangtze to the north, rebuilt Luoyang, reopened the Silk Road, and threw three enormous armies at Goguryeo. The last of these broke the country: millions were conscripted, the rebellions began, and in 618 his own guards strangled him at Jiangdu.

Almost everything he built outlasted him and was used by the Tang; almost everyone who built it died doing so. The verdict of the histories — that he was a monster — was written by the dynasty that replaced him, which does not make it wrong.

Empress Xiao stayed with him to the end, and afterwards passed through the hands of rebels, the Turks and finally the Tang court, dying in Chang'an at over eighty.