#6 David Beckham
David Beckham is arguably the most recognisable athlete on the planet. His exemplary footballing career and incredible looks have springboarded him into stardom; popularly even having a movie name in his likeness.
While he may not be the greatest purely in terms of skill alone, there is a point in saying that no one has increased the popularity of the sport quite like him in the past few decades.
He was also chiefly responsible for increasing the popularity of the MLS after moving there in 2007, helping LA Galaxy vastly improve their brand name in the process. Beckham has also taken up various ambassadorial roles, helping develop Chinese football and helping promote the 2012 London Olympics.
His name carries weight to it and if you associate him to your football project, the likelihood of success automatically increases.