Among all the human beings who have ever lived:
1. Who has been photographed the most?
2. Who has been caricatured the most by cartoonists?
3. Who has been on television for the greatest number of hours?
4. Who has been physically seen in person by the greatest number of people?
Obviously, it might be difficult or impossible to give precise definitive answers to these questions, but here's what some folks have claimed:
1. Princess Diana
2. Richard Nixon
3. Regis Philbin
4. Pope John Paul II
I have a hard time believing Regis beat out Johnny Carson, but apparently in August 2004 the Guinness Records people officially recognized Reege for "most hours on camera".
As for #2, probably George W. Bush is giving Tricky Dick a run for his money. For #4, I imagine Queen Elizabeth II puts up some respectable numbers -- and come to think of it, so would any entertainment personality with a long career performing in front of very large crowds -- e.g. Bono, Elton John, Madonna, Michael Jackson, Paul Simon, etc.