Tonight's the night that thousands of fans of ER have been waiting for, the return of Jennifer Aniston! Oh wait, that's 30 Rock that she'll be on tonight. Never mind.

Actually, tonight is the night that Dr. Mark Greene (Anthony Edwards) returns to County to try to save the life of Dr. Banfield's sick son. As we told you last week, Greene isn't really alive and he's not a ghost. It seems that Dr. Banfield came to County with her son and husband, years before she became the new head of the ER, and Greene was the doctor who worked on her son. Her memory (and the flashbacks) are triggered by a current story where Banfield is trying to save the life of another child who comes to County.

Edwards isn't the only one who comes back. Since most of the episode takes place years ago, we also see Laura Innes as Dr. Weaver and Paul McCrane as Dr. Romano. Innes has a rather dramatic entrance in the clip after the jump!

(S13E13) I think ER may have reached a record here. I've lost count, but this could be the five millionth time that the staff at County General have encountered a pair of step-brothers whose father only loves one and not the other. And, the six millionth time that the father seemed to be a bastard. Also, unless I'm mistaken, this is the infinity plus one time that a doctor has confronted that parent and told them, in no uncertain terms, that he was an a**hole. It goes back to the very first days of the show when Dr. Ross (the dashing and dapper George Clooney) would berate a parent at least once an episode.

Man, I've been watching this show too long! This week, the Ray-Neela-Gates love triangle continues, Pratt is in trouble with the law, Abby discovers why Eddie is really in Chicago, and Laura Innes says good-bye to ER.

So, what are you dawdling around for? Let's get going!

For those of you who watched last week's ER and thought, "Whoa! Weaver got fired?!", you're not alone. But if you also thought that there might be an opening for Laura Innes' character to stick around, you'd be wrong. Innes tells TVGuide.com that she's definitely leaving the show after tonight's episode; she may come back for an episode or two next year, but that's about it.

(S13E12) Well, that was unexpected.

Laura Innes' character, Doctor Kerry Weaver, wasn't in many episodes over the last few years, but it looked like she was coming back into the normal ER fold. It started late last season when the issues with her degenerative hip condition were resolved, allowing her to walk freely without the need of a crutch. Then, after preventing Kovac from getting fired, she was demoted back down to the ER as a mere attending. She became a medical reporter for a local Chicago news broadcast, and she began dating her segment producer. Things were looking up for Kerry.

Now, it looks like she's leaving for good.