From the Guinness World Records 2010 Gamer's Edition:
"Most Recognizable Video Game Character: Mario? Sonic? Mega Man? Nope, it's Namco's very own Pac-Man. 94 percent of American consumers recognize the pellet-gobbler, edging out Nintendo's plumber by just one percent."
I find that hard to believe. I think there are many more people who know who Mario is than pacman. But hey whatever that's just my opinion.