Have you ever heard of Nate Silver? Does Judith Jameson ring a bell? The editors at TIME magazine certainly hope so since the political analytics guru and director of Alvin Ailey dance troupe, respectively, both made the 2009 TIME 100, the magazine's compilation of the 100 most influential people on the planet [source: TIME]. But having an impressive sphere of influence doesn't necessarily imply fame or celebrity. Aspiring dancers would probably leap for joy at a chance to meet Jameson, for instance, while armchair pundits would prefer a lunch with Silver.

Assessing someone's fame isn't as simple as, say, measuring wealth. In 1966, when John Lennon famously said that The Beatles were more popular than Jesus, no one could judge definitively whether the rock star was off his rocker because no standard unit for fame exists. Given the hordes of screaming fans who greeted the Fab Four at every stop, who was to say that they weren't, in fact, overshadowing the Christian figure?

For one thing, Lennon might miss the mark on the basis of facial recognition. At the time, European and American youth probably recognized The Beatles instantly, but an image of Jesus Christ certainly would've been more identifiable to people around the globe.

Therefore, if we define fame in terms well-known faces, Queen Elizabeth II is certainly in the running for the most famous person of all time. With her reign approaching its sixth decade, the British Queen's visage has graced money, stamps, postcards and even an Andy Warhol screen print. In fact, aside from Jesus, she might have the most reproduced portrait in the world [source: Edwards]. On the other side of the pond, Che Guevara's iconic portrait, based on a 1960 photograph by Alberto Korda, is arguably as recognizable and reproduced. The Cuban revolutionary's somber stare shows up on T-shirts, posters and a hodgepodge of other merchandise as well [source: Holmes].

But judging on the basis of facial recognition largely disqualifies Muhammad, one of the best-known historical and religious figures. The Islamic faith prohibits depictions of the prophet as a means to discourage idolatry, and in 2005, a Dutch newspaper stirred major controversy among Muslim communities when it published cartoon images of Muhammad [source: BBC News].

In that case, we must turn to hard data in this quest for the most famous person of all time. For that, the best resource probably lies in today's instant fame machine, the Internet.