Kim family
North Korea's leadership has been effectively dynastic, with the first three leader being members of the Kim family -- descendants of the first leader Kim Il-sung.
Trusted members of the Kim family are given senior administrative posts. Untrusted members of the Kim family either live lives of obscurity, or are targetted for assassination.
The second and third leaders have been Kim Jong-il and Kim Jong-un. Kim Jong-un, the current leader, is morbidly obese, reckless with his diet, and is heavy smoker. When he has disappeared for extended periods of time commentators have speculated that, either he has had to withdraw for treatment for a serious health concern, or that he has died, and survivors aren't ready to reveal his death. Although he is relatively young, commentators expect him to die soon.
Three other members of the Kim family commentators have named as likely successors are: Kim Pyong-il, Kim Jong-un's uncle; Kim Yo-jong, his sister and most trusted advisor; and Kim Jong-un's daughter Kim Ju-ae, who is just a school-child.
Kim Jong-un has had at least two family members killed. In the early months of his regime commentators believed he had chosen Jang Song-thaek, the husband of an aunt to serve as a mentor -- until Kim Jong-un ordered him to be executed by a burst of fire from an anti-aircraft cannon. He tracked down and had killed an older half brother, Kim Jong-nam, in a bizarre incident where two individuals smeared his face with the VX nerve agent.
Kim Jong-chul is another older brother to Kim Jong-un]]