December 24, 3 BC – January 15, 69: age 70
Nobody liked Galba. He succeeded Nero as Emperor of Rome, primarily by dint of showing up in Rome with an army shortly after Nero's death. There was a considerable anti-Nero faction that called for Galba to become emperor, and forced Nero to commit suicide, but it was Galba's arrival at the crucial time that made all the difference.
Unfortunately for Galba, he inherited a huge mess, and politicians who inherit messes are almost always unpopular, regardless of how relieved people are to get rid of the incumbent (US presidential candidates take note). Galba's first priority was to try to restore order to the imperial finances, and he managed to make himself extremely unpopular in the process. It didn't help that he was old, either. Within a couple of months legions began to refuse to swear allegiance to him. When he went out to punish the rebels (in a litter, he was so weak) he was killed. In his final moment he offered his neck, saying, "Strike, if it be for the good of the Romans!"
About 120 different people claimed credit for killing Galba, hoping to capitalize on his unpopularity. It backfired though; when the next emperor (Otho) was replaced by Vitellus, the 120-name list fell into his hands and he had every one of them executed.