Especially noteworthy is the difficult relationship between Werner Herzog and Klaus Kinski, which Werner documented in "My best fiend"
http://www.imdb.com/title/tt0200849/
Yeah, Kinski was a world-class A hole. I can't imagine somebody acting like this without getting punched in the face every now and then:
https://www.youtube.com/watch?v=MPKODzv1PD4