Neil Flynn

He auditioned for Dr. Cox and didn't get it. John C. McGinley did. But the producers liked Flynn enough to write a new character specifically for him, one intended to appear once and possibly not even be real. The Janitor started as a potential figment of J.D.'s imagination, a phantom bully haunting the hospital. Flynn had spent years doing serious dramatic theater in Chicago, winning a Joseph Jefferson Award before stumbling into improv at iO Theater under Del Close. That combination of stage chops and absurdist instincts is exactly what made the character outlast anyone's expectations.

From 2001 to 2018, he appeared in 397 episodes of network television across two shows without a hiatus. That's 182 as the Janitor on Scrubs, followed immediately by 215 as Mike Heck on The Middle, a stoic Indiana dad who couldn't be more different from his Scrubs alter ego. Almost no one outside TV nerd circles knows his name. He's on Shrinking on Apple TV+ now, where he blends comedy and emotional weight in a way that makes clear all that time in dramatic theater wasn't a detour.

The Janitor didn't have a confirmed real name until Scrubs was almost over. For eight seasons, the writers left it ambiguous on purpose, because they originally conceived him as potentially imaginary. Flynn reportedly improvised a chunk of his dialogue throughout, which tracks: he trained under Del Close at iO Theater, the same coach who shaped Bill Murray and John Candy. He co-founded Beer Shark Mice, an improv team with David Koechner, in 1998, and they were still performing 17 years later.