Maj Canton - October 2, 2009

To celebrate Law & Order's 20th season, we selected 20 performers who appeared on L&O when they were relatively unknown and then went on to become Hollywood celebs.

If you watch Law & Order, you know that the program needs an ever-changing list of guest actors since there's a different crime each week. And you also realize that L&O doesn't have many guest stars -- most celeb guests go on Law & Order: SVU instead. With so many performers and a keen eye for casting, L&O has discovered some incredible talent over the years.