It’s hard to believe, but it’s been over 30 years since ER first debuted. And with 331 episodes during the show’s run from 1994—2009, there have been A LOT of cast members over the years.

2.

Here’s Anthony Edwards as Mark Greene:

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And here’s Anthony Edwards now:

4.

Here’s Eriq La Salle as Peter Benton:

And here’s Eriq La Salle now:

6.

Here’s Gloria Reuben as Jeanie Boulet:

And here’s Gloria Reuben now:

7.

Here’s Laura Innes as Kerry Weaver:

And here’s Laura Innes now:

8.

Here’s Maria Bello as Anna Del Amico:

And here’s Maria Bello now:

9.

Here’s Alex Kingston as Elizabeth Corday:

And here’s Alex Kingston now:

10.

Here’s Kellie Martin as Lucy Knight:

And here’s Kellie Martin now:

11.

Here’s Paul McCrane as Robert Romano:

And here’s Paul McCrane now:

12.

Here’s Goran Višnjić as Luka Kovač:

And here’s Goran Višnjić now:

13.

Here’s Michael Michele as Cleo Finch:

And here’s Michael Michele now:

14.

Here’s Erik Palladino as Dave Malucci:

And here’s Erik Palladino now:

16.

Here’s Maura Tierney as Abby Lockhart:

And here’s Maura Tierney now:

17.

Here’s Sharif Atkins as Michael Gallant:

And here’s Sharif Atkins now:

18.

Here’s Parminder Nagra as Neela Rasgotra:

And here’s Parminder Nagra now:

And here’s Linda Cardellini now:

20.

Here’s Scott Grimes as Archie Morris:

And here’s Scott Grimes now:

21.

Here’s David Lyons as Simon Brenner:

And here’s David Lyons now:

And here’s Mekhi Phifer now:

23.

Here’s William H. Macy as David Morgenstern:

And here’s William H. Macy now:

24.

Here’s Angela Bassett as Catherine Banfield:

And here’s Shane West now:

And here’s John Stamos now: