The most important man in North Korea rests in a gray granite palace, beyond an X-ray machine, a metal detector and a moat. He is dressed in a black suit and is covered by a crystal sarcophagus, his body embalmed 17 years ago.

Yet from that position, North Korean founder Kim Il Sung — the nation’s Eternal President — could play the most critical role in a power transfer that involves his untested grandson and a ruling class potentially skeptical about the young man’s abilities.

Kim Il Sung is revered in North Korea, defectors and visitors to the North Korean capital say, far more so than his son and successor, Kim Jong Il, who died Dec. 17. Some experts say the latest dynastic succession depends on a credibility that only Kim Il Sung can provide. As Kim Jong Eun tries to take power, experts expect that North Korea — in its messages to the country — will associate the heir more with his grandfather than his dad.

“When North Koreans talk about Kim Il Sung, there can be no doubt the emotion is genuine,” said B.R. Myers, a professor of international studies at Dongseo University in Busan, who traveled to Pyongyang in June. “When they talk about Kim Jong Il, the language becomes more formulaic than stylized, and they begin to use the slogans. With Kim Il Sung, they use their own words.”

Since the announcement of Kim Jong Il’s death Monday, North Korea’s state-run news media have worked quickly to mythologize the nation’s next leader, thought to be in his late 20s. The Rodong Sinmun newspaper said he was “born of heaven,” and the Korean Central News Agency described his ability to hold a mourning nation together.

But in subtler ways, North Korea is emphasizing ties to Kim Il Sung, who died in 1994 of a heart attack. In recently commissioned portraits of a young Kim Il Sung, painters have revised the Great Leader’s appearance, giving him a haircut that resembles Kim Jong Eun’s. One street sign, which Myers said he saw during his trip to North Korea, pays tribute to the three Kims — but with a catch. The reference to Kim Il Sung, the middle component of the three-panel sign, towers over the references to Kim Jong Il and Kim Jong Eun.

“That is just a visual way of showing the message, which is that the whole country’s legitimacy rests on the Kim Il Sung myth,” Myers said.

Forceful dictator

The North Korean capital pays tribute to Kim Il Sung’s life story, including its many fables. Historical libraries there describe how he single-handedly defeated the Japanese in World War II. His 40-foot-tall statue, arms outstretched, overlooks the city. Pyongyang’s spirelike Juche tower, built to commemorate Kim Il Sung’s 70th birthday, contains 25,500 granite blocks — one for each day of his life to that point.

But he was also one of the world’s most forceful dictators, historians say, installed by Stalin to run North Korea as a puppet state of Moscow. He devised his own brand of Marxism — heavy on conservative nationalism — turning his country into “the world’s closest approximation of an Orwellian nightmare,” said Andrei Lankov, a professor at Seoul’s Kookmin University.

Kim Il Sung’s memory benefits largely because of what he didn’t live to see. In the mid-1990s, the country’s economy disintegrated. The public food distribution system collapsed; families no longer received rations of 540 grams a day. More than a million died in a famine. Those problems began during Kim Il Sung’s final years, but they became more a part of his son’s legacy.

“Kim Il Sung was a nationalist and a zealot, and he was ready to sacrifice as many people as possible,” said Lankov, who attended Kim Il Sung University in Pyongyang. “But he will be remembered very fondly, I fear, because in his day living standards were higher.”

‘Kim Il Sung is always with us’

The personality cult that North Korea cultivated for its Great Leader also gave him a softer side, less as a ruler than as a guiding spirit. Couples visit his statue on their wedding day, and children know him as the Eternal Sun. His avuncular portrait — chin raised, face glowing — hangs on walls and public buildings. Pillars on North Korean streets remind passersby that “Kim Il Sung is always with us.”

“Kim Il Sung is like God to North Koreans,” said one defector, Park Chung-shik, who lives in Seoul. “In a word, he is perfect.”

Connecting Kim Jong Eun with his grandfather’s era is a challenge — he was just a boy when his grandfather died.

But the physical similarities between grandson and grandfather might be the best starting point. The Associated Press recently reported that some North Koreans were moved to tears when they first saw Kim Jong Eun’s face, so close was the resemblance. Kim Jong Eun has the same high cheekbones and doughy jowls as his grandfather, though some media outlets in Seoul have suggested that is the result of plastic surgery.

“But Kim Il Sung had energy in his bright eyes. He had a warmer image,” said Ju Gyeong-bae, 41, who defected from North Korea in 2008. “Kim Jong Eun looks somewhat artificial and less humanlike. . . . Even people who remember Kim Il Sung’s love and grace, it will be harder to deceive them because they’ve gone through so many lies now.”

Special correspondent Yoonjung Seo contributed to this report.