U.S. media organization Forbes is famous for its long-established lists of the world's richest people. Now it has started a new list dealing with those who hold the most power in the world
But how does one define "power?" How does the spiritual power of a religious leader compare with the temporal power of a head of state? How does a journalist measure up against a terrorist?
Forbes says it wrestled with this problem for some time, before coming up with four criteria. First, does the nominee have influence over a large number of other people? Second, do they control substantial financial resources? Third, are they powerful in multiple spheres? Fourth, do they actively use their powers?
These criteria produce some odd results. For instance, Michael Duke, the president of the Wal-Mart supermarket chain in the United States, comes out as the eighth most powerful man in the world. That's a whole 35 places ahead of Russian President Dmitry Medvedev.
Medvedev, at No. 43, is only two places ahead of U.S. talk-show host Oprah Winfrey, and he lies one behind Vice Prime Minister Igor Sechin.
Sechin, a close ally of Prime Minister Vladimir Putin, is sometimes described as a sinister figure, the "Darth Vader" of the Kremlin.
By Forbes's measurement, he emerges as the second most powerful person in Russia, occupying place 42. But that's well behind Putin himself, who finishes third in the entire list.
After first-placed Obama comes Chinese President Hu Jintao. That's significant in view of the fact that political commentators are starting to view China as the only real rival of the world's lone superpower, the United States.
One of the most controversial names on the list is that of Mexican drug baron Joaquin Guzman.
Guzman, whose personal fortune is estimated at $1 billion, heads the Sinaloa cartel. He is reputedly hiding in the mountains of northern Mexico, with a price of over $2 million on his head.
Mexico complained to Forbes earlier this year when Guzman was included in a list of billionaires, saying he shouldn't be compared to legitimate businessmen.
Another potentially controversial listing is that of Al-Qaeda terror leader Osama bin Laden, who comes in at No. 37, just ahead of Pakistan's Prime Minister Syed Yousaf Gilani, and Iran's Supreme Leader Ayatollah Ali Khamenei.
The highest-placed woman on the Forbes' list is German Chancellor Angela Merkel, two spots ahead of U.S. Secretary of State Hillary Clinton.