Jennifer Aniston

"I don't think there was a sensitivity like there is now."

Both stars worked with the twin actors when they were children.

It's no surprise Jennifer Aniston's hair — a.k.a. "The Rachel" — made the list.

But was it really?

"Jennifer’s pretty much sold it to me that she’s not a morning person."

"We just literally channeled everything into Ross and Rachel."

From Charlie XCX to Brittany Spears...

The beloved cast reunites at the studio where it all began.

The show will have a ton of special guests.

Plus, see who's set to make a guest appearance.