The death by natural causes of Kim Jong-Il highlights a possibly unpleasant truth about repressive dictators: Many, if not most, end up living long lives and dying peacefully.

Those who live by the sword don't necessarily die by it, according to "The Great Big Book of Horrible Things: The Definitive Chronicle of History's 100 Worst Atrocities" (W. W. Norton & Company, 2011). In it, Matthew White tracked the fates of the leaders most responsible for the 100-deadliest human events. A majority, he found, lived out their natural life spans in peace.

"About 60 percent of the individual oppressors and warmongers who were most responsible for each of these multicides lived happily ever after," White wrote....