(NBC) — For many people, Sam Waterston is the ‘face’ of the original “Law & Order,” on Thursday, the actor says farewell to the legendary series.

As Waterston reflects on his decades of “Law & Order” one question comes to mind.

“Where did all that dark hair go? That’s what I wanna know,” said Waterston.

Waterston joined the third hour of Today on Wednesday to talk about his more than 400 episodes as District Attorney Jack McCoy.

“It’s a wonderful thing to look at the world through somebody else’s eyes and that’s what an actor gets to do,” said Waterston.

When the show was revived in 2022, after a decade away from TV, Waterston returned as well, but the clock was ticking.

“I knew I was going to leave when I came back, it was just a matter of when and this was a beautiful way to go, I have to say,” said Waterston.

In fact, Thursday’s farewell episode is entitled “Last Dance.”

“Thank you all very, very much for watching patiently over all these years,” said Waterston. “While I have not gotten tired of acting.”

And he still hasn’t, the 83-year-old might be leaving “Law & Order,” but he’s not retiring.

“Not on your Nellie,” said Waterston. “Not a chance.”

Waterston was not an original “Law & Order” cast member. He didn’t join the series until the show’s fifth season.

“Law & Order” airs Thursday at 8 p.m. on NBC4.