By Stuart Levine

NBC revisits its once glorious past tonight when Anthony Edwards returns to County General on “ER.”Er1

The numbers for “ER” have been good this year, the show’s 15th and final season. Credit strong marketing and consistently compelling stories. Audiences who were once glued have come back for a last look.

And expect an even bigger Nielsen turnout when one of the most favored alumni comes back.

Well, Edwards returns but his character, Dr. Mark Greene, who died of cancer, can’t. He’s shown in flashback, interacting with the icy Dr. Cate Banfield, so adeptly played by Oscar-nominated actress Angela Bassett.

Not to give anything away, but the two characters interact at a time that forever changes Banfield’s life. I’m never been one to fall for the “very special episode” marketing ploy that NBC used with almost every show at one time or another, but this one’s worth watching, especially if you go back to the early days of “ER,” when folks such as Edwards, George Clooney and Eriq LaSalle ran up and down the hallways.

On a conference call with reporters, Edwards said he was a bit hesitant to return to Stage 11 on the Warner Bros. lot, where he’d spent eight years, but felt the timing was right to come back. Yet, he still had butterflies

“You don’t want to screw it up, you know,” he said. “I think there’s a natural respect for this show that you want to, you know, be respectful of.”

And he was confident that if he returned, his character’s hard-earned reputation wouldn’t be tarnished.

“I knew they would take care of him. You know, it’s a funny thing. You feel as an actor that you own the character, but the truth is so do the writers. The writers really feel an ownership of Greene, so they want to do right for him. So, there’s actually more people looking out for you than yourself in the end.

Edwards, who appeared in David Fincher’s brilliant murder mystery “Zodiac” last year, has been heavily involved in charity work. He donated the money he would’ve received for appearing in this “Heal Thyself” episode to Shoe 4 Africa, in which he’s raising money to build a hospital. “ER” exec producer John Wells and Steven Spielberg also contributed.