PHOTO GALLERY: The Top Ten ER Guest Appearances

While the cast of ER has always been up front and center, through the years a handful of other recognizable names and faces have gone through the hospital doors.

As we bid a fond farewell to the groundbreaking drama, click here for a gallery of the best celebrity guest spots.

Some highlights: Kirsten Dunst plays a troubled teenager soothed by George Clooney, a post Sex and the City Cynthia Nixon plays a stroke victim, and Ewan McGregor is a convenience store gunman!

PHOTO GALLERY: ER's Top Ten Episodes and Legacy

The final episode of ER airs tonight at 8/7c on NBC.