Kim Jong Il, a Cold War-era leader in modern times

Disputing accounts that Kim was "peculiar," former U.S. Secretary of State Madeleine Albright characterized Kim as intelligent and well-informed, saying the two had wide-ranging discussions during her visits to Pyongyang when Bill Clinton was U.S. president. "I found him very much on top of his brief," she said.

Kim's marital status wasn't clear but he is believed to have married once and had at least three other companions. He had at least three sons with two women, as well as a daughter by a third.

His eldest son, Kim Jong Nam, who is about 40, is believed to have fallen out of favor with his father after he was caught trying to enter Japan on a fake passport in 2001 saying he wanted to visit Disney's Tokyo resort.

His other sons include likely successor Kim Jong Un and the heir-apparent's older brother, Kim Jong Chol. Their mother reportedly died several years ago.

Lee reported from Seoul, South Korea.