One aspect of Star Wars that's passed into legend is the sheer volume of people who auditioned for parts. Among those turned down were Kurt Russell, William Katt, Amy Irving, and Karen Allen. Even Billy Dee Williams didn't pass his original test, for the part of Han Solo.
Here are a couple auditioners who did make the grade, both working with Harrison Ford: Mark Hamill...
...and Carrie Fisher.
Here's one who didn't: Cindy Williams, pre-Laverne & Shirley.
Finally, here's a funny look at other auditions, with Kevin Spacey yet again breaking out his killer Christopher Walken.