ER Is the Only Real The Pitt Successor — and It Still Has One Big Advantage

If you love medical dramas with big emotions, wild cliffhangers, and characters you actually care about, it probably all started for you (like it did for me) with something like Grey's Anatomy. These days, though, The Pitt on HBO Max is giving me serious reasons to keep binging. I started the series when it hit in January 2025 and, honestly, it does a lot of things right: more grounded tone, even better writing than most shows in this genre, and an absolutely killer (sometimes literally) Season 2 finale. Still, as much as I enjoy The Pitt, there's one legendary series that set the bar for everyone else: ER.

Why ER Still Sets the Gold Standard for Guest Stars

Almost every hospital show brags about the sheer talent of its casting, but nobody has done the guest star game quite as well as ER. Sure, The Pitt has sprinkled in quality talent—I’m still thinking about Samantha Sloyan’s gut-punch of a performance as the mom who loses her kid to an overdose—but ER basically made it an art form to have famous (or soon-to-be famous) faces show up and contribute in a way you actually remember years later.

For anyone who doesn’t know, ER ran for a whopping 15 seasons, all about the chaos and drama of Chicago’s Cook County General Hospital. The regular cast was stacked: George Clooney, Noah Wyle, Julianna Margulies, Angela Bassett—the list is kind of ridiculous. But here’s where it gets impressive: the guest stars didn’t just wander on and disappear without impact. Their storylines usually packed a punch and told us something brand new about the main characters too.

The Guest Stars Who Stole the Show

Let me break down some of ER’s most memorable guest star moments by season, so you can see what I’m talking about:

• Season 1: Bradley Whitford showed up as Sean O'Brien in the heartbreak machine known as 'Love's Labor Lost.' If you like your drama with tears and real stakes, this episode is brutal. Whitford goes full devastation as a soon-to-be dad in a nightmare delivery. Also, Kathleen Wilhoite played Chloe, the train-wreck sister of Dr. Susan Lewis (Sherry Stringfield). Chloe’s substance abuse problems dig deep into Susan’s own backstory, showing us that the always-in-control doctor is really the designated grownup in a dysfunctional family. It’s the kind of backstory device that a lot of shows never bother to get right.
• Season 2: Lucy Liu played Mei-Sun, a mother dealing with her young son’s AIDS diagnosis—a storyline that was way ahead of what most shows even attempted to tackle back then.
• Season 3: Kirsten Dunst guest starred as Charlie Chiemingo, a runaway teen whose story is a lot darker and more authentic than most of the soapy teen stuff you saw on TV in the '90s.
• Season 7: Wentworth Miller (before Prison Break made him a star) played a football player with heart trouble, letting the show tackle the pressure and real dangers of pushing too hard for athletic glory.
• Season 14: Steve Buscemi popped up as a guy in the witness protection program—a total curveball storyline, but Buscemi makes it sing.
• Season 15: Susan Sarandon and Ariel Winter (pre-Modern Family) played characters dealing with grief and tragedy after a car accident. Sarandon in particular gets a showcase that would have been the centerpiece of a whole season on some shows.

Sometimes the Guests Outshone the Stars

One of my personal favorite examples of a guest role outshining even the main cast is when Bob Newhart showed up in Season 10’s 'Death and Taxes' as Ben Hollander, a guy losing his eyesight and unraveling mentally. The episode spends real time with his fears and struggles, and Dr. Lewis (again) gets to show her human side way beyond the usual medical heroics. I honestly can't think of another medical drama where a guest character like Ben felt like the actual heart of an episode.

So, while I’ll give full credit to The Pitt for delivering two seasons worth talking about, there’s just no arguing that ER raised the bar with how it used guest actors—not just for stunt casting, but to give us something real, sometimes even something unforgettable. Rewatching it now is basically an A-list actor scavenger hunt, if you’re looking for an excuse to head back to the '90s.

'Without seeing this family dynamic, we might only have seen Susan as an ambitious doctor who can get through anything. Chloe's presence gives her more layers.'

Bottom line: If great guest performances are what you’re after, ER still stands alone. But hey, The Pitt sure is fun to talk about—let’s see where it goes as more seasons roll in.