Now, [redacted] years later, I've confirmed both those things are still true by rewatching all 15 seasons of the medical drama. Hide Caption 4 of 16 Photos: 16 celebrities you forgot were on 'ER' Randall Park – Park plays a man with developmental delays whose teenage sister has a baby in the ER in a Season 11 episode. Hide Caption 12 of 16 Photos: 16 celebrities you forgot were on 'ER' Keegan-Michael Key – The comedian appears (with hair!) Hide Caption 15 of 16 Photos: 16 celebrities you forgot were on 'ER' Dean Norris – The "Breaking Bad" actor helps Dr. Greene diffuse a bomb in Season 5's "They Treat Horses, Don't They?" Hide Caption 16 of 16Reinvention is hardSlumps are an accepted reality of any long-running TV show, regardless of what producers claim, and "ER" was not immune.

Source: CNN May 24, 2019 16:52 UTC