Wizards have been an essential element of fantasy movies since the dawn of the cinema. Essentially, you can't hope to have a universe of dragons, trolls and adventurous men with names like "Numedor" without including a powerful wizard who is there to lend a magical hand when the going gets tough.
Unfortunately, not every wizard in film history has stepped up, and some seem to flat-out prefer cashing in their wizard pensions and spending the rest of their 2,000-year lifespan as the door greeter at Walmart than perform their expected duties.
Albus Dumbledore (the Harry Potter series)
Dumbledore is the headmaster at Hogwarts School of Witchcraft and Wizardry, and basically the most powerful damned wizard in the Harry Potter universe. He's a kindly old man, which is a good thing because he can turn invisible, create objects out of thin air, read minds, shoot fire, whatever. He's pretty much a god.
Unfortunately, most of the time he gives kind of boring speeches and makes a teenage boy do everything that he, being nearly all-powerful, should probably be doing instead.
The case against him:
Fans of the Harry Potter series have uttered the phrase "Where the crap is Dumbledore during all of this?" more than once. He's usually away on business when Harry and his friends are in imminent danger of attack, and the three of them are usually left to either figure out difficult riddles or single-handedly fight humongous snakes, a giant troll, an army of gigantic spiders--pretty much every horror imaginable. And when he says he's away on business, you know he's probably just hanging out in his apartment in his wizard underpants watching the wizarding equivalent of Frasier reruns.
Consider Prisoner of Azkaban, where in order to save a friend he casually advises Hermione to use a "Time Turner" device, which lets you effortlessly go back in time and change any thing you want.
Wait, what? Why didn't he go back in time and deal with it? Or better yet prevent all those things from happening with his wizard powers? Why not go back and prevent the birth of the wizard Antichrist, Voldemort? And in the 6th book, he actually dies. The man can travel through time, but he couldn't prevent his own freaking death?