CinemaBlend
Considering how long medical dramas like
ER tend to last, how often cast members rotate, and how frequently it require new actors to play the patient(s) of the week, the cast list is unsurprisingly, but still impressively, large. The aforementioned NBC series lasted 15 seasons (from 1994-2009) and made A-listers out of George Clooney, Don Cheadle, and Julianna Margulies to name just a few, but did you know Chadwick Boseman was a guest star before he became a household name?
The late, Marvel movie alum is far from the only beloved celebrity to make an early appearance on
ER. In fact, we found an overwhelming amount of notable names to choose from, but settled on a still sizable 20 to include below, starting with one of the busiest and most respected actresses of her generation.