Katherine Heigl
Katherine Heigl was a very popular actress at the height of her career. Apparently, that demand got to her head and she became a classic Hollywood diva. She's been quoted as "horrible to work with" on and off-set, which is something you never want to have on your record.
Tough to Work With
According to people that worked with her, she would constantly question and edit her script without permission from the directors. She would refuse to leave her trailer if things weren't going her way, wore uncharacteristic outfits to shoots that the stylist did not approve of, and, of course, act like a bully to all lower-ranked employees. Heigl has been heavily blacklisted.