Get ready for a mini ER reunion of sorts on Law and Order: Special Victims Unit. Anthony Edwards, who played Dr. Mark Greene on ER for eight seasons, will be guest starring in an episode in SVU‘s upcoming 18th season, according to Entertainment Weekly.

The guest starring role will reunite Edwards with Mariska Harigtay, who played Cynthia Hooper for 13 episodes of the fourth season of the show. Hargitay and Edwards’ characters had a relationship during Hargitay’s brief tenure on the show.

Details about Edwards’ character on the show have yet to be announced.

Edwards isn’t the only well-known person to be guest starring in the upcoming season. Back in July, it was announced that Vice President Joe Biden would be guest starring as himself in the second episode of the season. Henry Thomas, better known as Elliot Taylor from ET, and Kelli Williams, who’s known for her roles on Lie To Me and Army Wives, will also be guest stars this season.

Edwards is most known for his role as Dr. Mark Greene on ER, a role he held for eight seasons before leaving the show to pursue other acting opportunities. He was one of the original characters on the show and was the only of the original characters who died, with the other original characters being written off the show at some point during its 15-season run.

His death was revealed to viewers in a scene where John Carter (Noah Wyle) reads a fax that Mark sent to the hospital from his time in Hawaii. He receives two faxes, one from Mark and the other from Elizabeth Corday (Alex Kingston), his wife, saying that he’d passed away that morning.

Edwards appeared in the final season of the show, when ER aired a flashback episode that featured Mark treating a patient shortly after the news that his brain tumor came back and was declared truly inoperable, as his first brain tumor was initially declared inoperable but was eventually taken out by a doctor in New York City.

Law and Order: Special Victims Unit has its 18th season premiere on Wednesday, Sept. 21 at 9 p.m. Catch up on the most recent season on Hulu and Netflix. Hulu has every single episode from all the seasons available to stream and Netflix has seasons 13 through 17 available to stream. ER isn’t available to stream anywhere.