There have been plenty of them: Beria, Stalin's hated secret policeman, was ruthless and insatiable and even the dying Brezhnev had an affair (with a nurse, of course). But the unchallenged champion was Ivan the Terrible, who had seven wives and a covey of mistresses to whom he would turn whenever he felt the need for a breather from laying waste the countryside.
Yet, vile though he was, the tsar occupied higher moral ground in one sense. At least he was good at atonement. When his conscience got too much for him, he set off barefoot on a pilgrimage to pray and fast in an Orthodox monastery, before returning to Moscow for more inappropriateness.
Mr Clinton looked subdued yesterday during his first encounter with the press since his prime-time admission over the Monica Lewinsky business, but he has still not mastered the art of penance.
"I have actually been quite heartened by the reaction of the American people and leaders throughout the world about it," he said, after the first Monica question from the White House press corps, who have not been diverted from the subject by trifles such as a sinking Russia and global recession.
To give him his due, Mr Clinton did try: "You know, I have acknowledged that I made a mistake, and said I regretted it, and asked for forgiveness," he said. But that was not enough contrition. They wanted a word that this litigiously minded president can never give: Sorry.
Do you, he was asked, feel that after all the disappointment over "the broadcast" "you need to offer an apology, and do you have any feeling that the tone of your speech didn't quite convey the feelings you had?"
Even in his reply, Mr Clinton could not quite bring himself to use the a-word. "I thought it was clear I was expressing my profound regret to all that were hurt and to all who were involved and my desire not to see any more people hurt by this process and caught up in it."
Mr Clinton should have taken a leaf out of his host's book. Mr Yeltsin was asked only one tough question: would he be prepared to dissolve parliament if it refused to confirm his choice of prime minister, Viktor Chernomyrdin? But he clearly forgot what it was. "Well, I must say, that there will be a reasonable number of events taking place in order for us to be able to obtain these goals. ... What?" he replied opaquely.
Mr Clinton was terribly impressed: "That would have been my answer too! That was pretty good!"