Lucy Liu and Bill Murray
Bill Murray isn't someone who is easy to get along with. In fact, he's quite hard to keep up with! He ended up starting this feud with Lucy Liu during a scene they were shooting for Charlie's Angels. He was quoted saying, "I get why you're here, and you've got talent... but, what in the hell are you doing here? You can't act!" Ouch!
Sarah Michelle Gellar and Alyson Hannigan
These two were all over TV screens in the '90s. They starred in Buffy The Vampire Slayer together and were known to have gotten along pretty well. Things took a turn for the worst when Gellar told the public that she was leaving the show... before she told anyone else. That, apparently, was the last straw and their relationship was totally tarnished.