Bad Casting Choices in the Movies and Television

Optimus Prime said
John Wayne as Genghis Khan is one Hollywood's most famous miscastings

But there is another equally head scratching one

I just watched The Wind and the Lion from the mid 70s with a young (and hot) Candice Bergen, I really only know her starting from Murphy Brown

and starring Sean Connery playing an Arab Chieftan sounding exactly like Sean Connery

One of Arnold Swartzenaggers most well known movies was almost ruined by bad casting. Jean Claude
Van Damme was cast as the original Predator. He filmed the fist few scenes. When the director saw how
much the other actors towered over the 5'9 Van Damme. he decided he wasn't intimidating. He then
chose 7'2 actor Kevin Peter Hall.