Herzog's first choice for the role of Aguirre was actor Klaus Kinski. The two had met many years earlier when the then-struggling young actor rented a room in Herzog's family apartment, and Kinski's often terrifying and deranged antics during the three months he lived there left a lasting impression on the director. Years later, Herzog remembered the volatile actor and knew that he was the only possible man who could play the mad Aguirre, and he sent Kinski a copy of the screenplay. "Between three and four in the morning, the phone rang", Herzog recalled. "It took me at least a couple of minutes before I realized that it was Kinski who was the source of this inarticulate screaming. And after an hour of this, it dawned on me that he found it the most fascinating screenplay and wanted to be Aguirre."