When I think of this question, I immediately think of Gene Simmons and Axl Rose, and to a lesser extent, Dave Mustaine. Gene Simmons more in the general sense of arrogance, and Axl because of arrogance and because he's a gigantic diva. For what it's worth, I love all of the bands and music that these guys were a part of, and I understand that you have to have some ego to be a star in a band like this, but these guys really take it to another level. While I'm not really a fan of Poison, Brett Michaels seems like a genuinely good guy.
*I would rather not start talking about rappers, as that's obviously a whole other league.