Charondas
Forced himself to commit suicide in 6th Century BCE
Charondas was a lawyer in Sicily, and he created a law that stated anyone carrying a knife into a political assembly must be executed. One day, he went hunting and was called into the office, and he forgot to remove his knife. So he was forced to execute himself.
There is a video of this on YouTube (honest). You can tell he was afraid to jump, but his handlers kept telling him it was too late to back out.
So all the way down, when he knew he was going to die, at least he had the satisfaction of being able to yell "I told you so!"