SOO MANY left over the years and never returned, some did make appearances, Carter, he left in S. 11 and came back shortly in S. 12 for those africa shots and then never to be seen again until S. 15. I guess that's why he never put his name on the wall, He's still in county, I think he always will be..
I'm only naming the ones I know off the top of my head.
Doug left county because he had no life there anymore and later on Carol joined him. We all knew that'd happen.
Lucy-She left ER(& not in a good way) and took alot of the fans hearts with them.
Malucci-I wasnt so fond of him but I do remember him...
Mark Greene - Now this guy, really touched my heart and I didnt expect him to, he grew to be a really popular character and his romance/marriage to Elizabeth Corday really hooked alot of fans. Him dying broke my heart but in a way, he did return to County(HEAL THYSELF), just not in the way some would think..Even after his death, his presence remained apart of ER and always would.
Romano -A nutty guy but you gotta love him for it, his death was CRAZY and also he returned to County in a way as well...IE Heal thyself.
Elizabeth Corday-I absolutely loved this character, she was one of my all-time favorites and will always be. She Left ER b/c she truly had no life there anymore, Mark gone and alot of others, It hurt to see her go in S. 11 but was happy to see her return again twice(One in Neela's dream I THINK and In the season finale with Rachel)
Chen- She wasnt a HUGE favorite of mine but after her father died, she was NEVER seen again, I still would of liked to know what happened to her. She left in S. 11 I believe.
Susan Lewis-A great character, left ER b/c of not getting the job she wanted, but returned in Series finale S. 15.
Greg Pratt- GREAT character, he stuck it out for a long time, I would of loved to see his character not be killed off but he left ER Leaving amazing memories for his fans..S-8-S-15
Gallant- Also a nice character but to me, the very few guest appearances that he did after he left in S. 10 werent enough. He got with Neela too quickly and married her too soon.
Neela- One of my favorites, I love her, she's got so many sides to her tho, she started off as a naive nerdy student into a respected surgeon, her marriage to Michael I didnt approve of too much b/c one, it was too rushed, Her contiuning blossoming romance with her beloved roommate ray, now that was my absolute favorite...<3 However, her fear/guilt of going after ray got to me over the years and almost made lose faith with her, her nasty flings with Tony and Simon really disappointed me, however in S. 15, she really proved something to me, she grew up, she became a person that was nothing like the old neela i saw in S.11-13, I didnt expect her to leave to County but Im happy she did, she made the right choice and left to be with Ray. <3
Ray Barnett- A rocker doctor, he's got such a heart, the more I saw of that, the more I loved him. Him falling for Neela and seeing him go through such hell broke my heart, I really thought he'd never get her, b/c one she's a really naive gal regarding love. Him Leaving the way he did in S. 13 also killed me and he SHOULD of came back in S. 14 for some guest spots, they should of evolved ray's character more but ultimately, when he left county, it was for good and he only returned to snag the heart of the woman he loves and just his visit back in county at halloween was enough b/c after that, i KNOW he took her heart with him. Overall, Ray was never going to be a guy who stayed at county forever..
Abby-AWSEOME character, I've always loved her, especially with Luka, her love story with luka snagged fans hearts and the baby joe thing got it even more, I knew eventually she'd leave, b/c after luka left, she truly had no life there anymore and when she left in S. 15, it was for good...but it was great to see her in 15.20 in a phone call..
LUKA-troubled soul but i loved him, his romance to abby was great and to me, it was the only person he fit well with, him leaving in S. 13 sucked as well but not for long since we had some guest spots in S. 14 and S. 15..
Weaver-A crazy lady but I truly respected her, her marriage to sandy was great and also hurt when sandy died, i truly thought weaver would be the type to stick around in county but i was wrong, sad to see her leave in S. 13 but to return in S. 15 twice was a treat.
Morris-HILARIOUS character, he never left tho, he still remains at county, I NEVER once thought he would be...
Gates-His butting in on the roomie storyline pissed me off and i grew to really hate him but in S. 14, i got a chance to grow a new opinion of him again and start over so I didnt hate him anymore after that...but weird, hes still at county...
Brenner-I didnt like this guy from the start, another complication for the roomie storyline and funny that hes STILL IN COUNTY...
SAM- she never left either, a spontanous gal at that....
Banfield-Another version of weaver,i think she'll stick around county for a long time since the original weaver retired from county lol.
I may be missing some but eh. Its weird. the ones I thought wouldnt stick around county for long, ended up staying until there....Morris,Carter,Sam, etc..
I look back and its so weird, I never thought Neela would leave county.....but she did...