I don't get to see $100 bills very often and so I've never paid attention to the picture of Ben Franklin on it. But the controversy about the U.S. government messing up on $100 bills got me looking more closely. The picture on the $100 bill looks a lot like the late Jack Benny. Here's the best picture I could find in the wikipedia entry (Jack Benny is third from the right):
Here's a link to the best one I could find but I'm not putting it here because I'm concerned about copyright. (Scroll down to the bottom.)
And now look at the picture of Benjamin Franklin on the $100 bill.