The beauty of there being so many actors in the realms of moviemaking is that everybody has their own personal favourites. It's tough to describe why, exactly, you like a certain actor; something unexplainable draws you to them, and it's not easily put into words. Being asked why you favour Al Pacino over Robert De Niro only really results in a reply like: "He's just more... visceral. I don't know... he's just... great!" We tend to follow our favourites wherever they venture, of course, supporting them and singing their praises for as long as they continue to entertain us. That is, until they wind up doing something that forces you to re-evaluate everything you thought about them up to that point. It's difficult for a single movie to change your perceptions of an actor you love, but in the cases of the 10 actors we've assembled here for this list, that's presumably what happened to their fans when they laid eyes upon the associated films. It's not just that the movies listed here are bad; it's that the actor involved should have never been a part of them in the first place. Watching them on-screen felt like being punched in the chest by an old pal... Why, guys? Why did you make us think differently of you? Don't you know that we loved you?