The life of Princess Leia immediately following Star Wars: A New Hope was one, ironically, of hopelessness. Carrie Fischer was so typecast as the space heroine that she was unable to get much work elsewhere, and she took solace in drugs. During the filming of Empire Strikes Back, Fischer was knee-deep in her cocaine addiction. She routinely got high on set, particularly before any scene that found her on ice planet Hoth, for whatever reason. Maybe the coke helped her stay warm on the fictitious planet? Fischer says she "didn't even like coke that much, it was just a case of getting on whatever train I needed to take to get high. Which is super depressing, considering that she was taking part in what is arguably the greatest installment in one of the most beloved franchises ever made.
