Darth Sidious, a pretty good run.
His accomplishments far outweigh his failings. I mean sure he got killed in ROTJ, but he had a pretty good run didn't he?
He destroyed the Republic and gave birth to the Empire, he wiped out the Jedi who had been the guardians of the Republic for millenia, he ruled with an iron fist for 30 years!!!
It had to end some time...sure he was a little too arrogant in the end, but he did all he set out to do, he got to the top of the mountain, it had to end sooner or later...but come on, it was a pretty good run.
Here's to Darth Sidious, you may not like him, but it just goes to show with some hard work and a determination you can be whatever you want to be.