Young and inexperienced, Kim Jong-un is seen as poised to take over North Korea with the death of his father and extend the Kim dynasty's rule over the reclusive state for a third generation.
Not much is known about the younger Kim, not even his age, though his father, Kim Jong-il, and his autocratic regime had begun making preparations for the son's transition to power.
Thought to be aged around 27, Kim Jong-un Had already been made a four-star general and occupied a prominent political post when he was reported to have made an important diplomatic visit to neighbouring China in May this year.
On the trip, he introduced himself to the destitute North's main benefactor, possibly one of the most crucial diplomatic moves he will ever make.
"The rest of the world is going to have to look at someone who is basically a kid as having China's support to be the North's next leader," Yang Moo-min, of Seoul's University of North Korean Studies, said at the time.
The youngest of the leader's three sons, Kim was most likely born in 1984. His name in Chinese characters translates as ‘righteous cloud’ while the media calls him ‘the young general’.
Educated in Switzerland, he is thought to speak English and German, and bears a striking resemblance to his grandfather, the North's founder, Kim Il-sung.
Analysts say two attacks on the peninsula last year, which killed 50 South Koreans, were aimed at winning the army's support for a continuation of dynastic rule and underscored an intent to maintain the state's military-first policy.
Experts say the young Kim is likely to follow the same militaristic path, maintaining a strong grip over one of the world's largest armies and pressing on with a nuclear weapons program in the face of international outrage.
SUCCESSION PROCESS
Last year, the young dauphin was officially anointed as leader-in-waiting when his father made him a four-star general and gave him a prominent political post. But for added security, Kim promoted his sister and her husband to top positions to create a powerful triumvirate to run the family dynasty.
Despite speculation that Kim Jong-il's rule was nearing its end, after he reportedly suffered a stroke in 2008, the ‘Dear Leader’ increased his workload and appeared to be physically stronger in recent months.
There have also been few signs of regime change, with no overt signs of crisis or instability.
"Despite economic hardship, food shortages, and a welter of sanctions, the Kim Jong-il regime seems stable, and the succession process is, by all appearances, taking place smoothly," John Delury and Chung-in Moon of Yonsei University wrote in an article in April.
Moreover, the two scholars say China is actively engaged on diplomatic and economic levels in supporting North Korea's survival, stability and development.
China prefers the status quo on the peninsula, worried that if the South takes over the North, the South would bring its U.S. military ally to the Chinese border.
CLOAK OF SECRECY
The most frequently viewed photograph of Jong-un before his emergence last year was of him as an 11-year-old. But recent pictures and footage of him show a heavy-set young man with his hair clipped short to resemble the young leader Kim Il-sung.
There is a question over whether his late mother, a Japanese-born professional dancer called Ko Yong-hui, was Kim Jong-il's official wife or mistress -- an issue that might weigh on his legitimate right to replace his father.
Even by intensely secretive North Korean standards, remarkably little is known about the son, whose youth is also a potential problem in a society that values seniority.
Kim Jong-il was very publicly named heir by his father, Kim Il-sung, but he studiously avoided repeating the process and for years none of his three sons appeared in state media.
Kim Il-sung, the "eternal president", died in 1994.
After taking over from his father, Kim Jong-il saw his state's economy grow weaker and a famine in the 1990s killed about one million of his people, while he advocated a military-first policy.
In a book about his time as chef to the ruling household, Kenji Fujimoto of Japan said that of the three sons, the youngest, Kim Jong-un, most resembled his father.
He is also said to have a ruthless streak and the strongest leadership skills of the three. He was also thought to be his father's favourite.