Acting is really fun career, and most people would do anything to break into the business. But it's not when you have to work with these actors -- they just seem to suck all of the fun out of the experience when they're on set. Some of them might just surprise you!
William Shatner is pretty well known for not getting along with his co-stars, epecially his long-standing feud with George Takei. That's given him a reputation for not wanting to do what he's told on set, and even at conventions. A particularly grievous account comes from a 2004 convention where he actually said that he didn't want to "deal with all this Alzheimer's crap", referring to Star Trek co-star James Doohan's recent diagnosis and the event in his honor at the convention.