Albus Dumbledore
Comparing Dumbledore in the first two Harry Potter movies with Dumbledore in "Harry Potter and the Order of the Phoenix" is like looking at two entirely different people. Oh, how the man has changed. Wait, it is two different people. The original actor who played Professor Dumbledore, Richard Harris, died of cancer after the second movie wrapped. Michael Gambon replaced him for the next three movies, wearing a shorter, darker beard clasped occasionally by a sort of ponytail holder thing. We don't care how hip this is with the elderly wizards; it's just not a good look.