Around 2000, Ad Age ran an article where they presented their Top 10 advertising icons of all times. The criteria they used included sales and "cultural impact". It's not really surprising that Tony the Tiger, Ronald McDonald, Pillsbury Doughboy (woohoooooo), Aunt Jemima, Betty Crocker, the Green Giant, Michelin Man, and the Marlboro Man (see http://adage.com/century/ad_icons.html) made the list. One thing they have in common is that they have been around a long time. Aunt Jemima was introduced in 1893. The Michelin Man, 1898. The youngest character is the Energizer Bunny- and she's just entering her sexy 20s.
Eventually a Top 10 brand icon list will get revisited. When it does, there may new entrant: the Most Interesting Man in the World. His reputation may not be expanding faster than the universe, but it sure has spread a lot on You Tube with millions of ad views. His ads are certainly are effective too. Earlier this summer when imported beer sales dropped 11% - Dos Equis sales rose almost 20% (AdAge). This puts Dos Equis' sales on par with Stella's in North America. But, what about his cultural impact? He may have longevity as some kids say that when they grow up they want to become the most interesting man in the world. http://www.youtube.com/watch?v=Brkx_6wKNhQ. Now that's interesting.
For what its worth, Johnathon Goldsmith (the actor who plays the world's most interesting man) used to star in McGyver, Magnum and Murder She Wrote. Evidently Angela Lansbury from Murder She Wrote would question him just because she found him so interesting.