In the mid-1970s, George Lucas was casting a strange science fiction film called Star Wars. He was looking for fresh faces, which is why he told his casting team that actors from his previous film, American Graffiti, were off the table. That meant Harrison Ford, who had appeared in American Graffiti, was not allowed to audition.

He showed up anyway. Not as an actor, but as a carpenter. Ford was working odd jobs to pay the bills at the time and had been hired to install a door at the American Zoetrope offices in San Francisco, where Lucas was holding his casting sessions. The casting director, Fred Roos, who believed Ford was right for the film, had quietly arranged it that way.

While Ford worked, Lucas asked him to read lines with the actors auditioning for the role of Han Solo. Ford agreed, as a favor. He read the part of Solo with actor after actor, day after day, while Lucas watched. Some 500 people later, it slowly became apparent that the man feeding lines to everyone else was better than any of them. Lucas cast Ford as Han Solo. 

Jack Nicholson, Robert De Niro, Kurt Russell, Christopher Walken, Burt Reynolds, and Nick Nolte all came in to read for the part. Al Pacino was offered a fortune to take it. He turned it down because, as he later put it, he could not play something if he did not speak the language. 

Harrison Ford, the carpenter who was not supposed to audition, went on to play Han Solo in five films across four decades. Pacino, who later quipped that he was "in the mood to make Harrison Ford a career," did just fine too.