7. Bette Davis & Joan Crawford (What Ever Happened To Baby Jane?)
Robert Aldrich's 1962 classic What Ever Happened to Baby Jane? is a story of a bitter feud between two women that spirals out of control and escalates to the point of physical violence. Coincidentally, that's the plot of the movie too.
The rivalry between Joan Crawford and Bette Davis was legendary long before they co-starred in this film. They took swipes at each other in any publication that would print them, and Aldrich sought to channel their mutual hatred on screen.
Channel it he did, but he also had his work cut out preventing them from doing each other serious harm between takes. At one point, Crawford injured herself tripping over a bunch of Coca-Cola bottles Davis had lined up outside her dressing room door, a petty reference to her having married the president of Pepsi.
When filming an alternation between their characters, Davis delivered a very real kick to her co-star's face, causing a wound that required stitches. Crawford got her revenge while shooting a scene where Davis had to drag her lifeless body along the ground, lining her dress with lead weights so her rival pulled a muscle.
The entire What Ever Happened to Baby Jane? shoot was one epic on-set meltdown after another.