ET has the 411 on just what Jennifer Aniston will be doing when she joins the cast of "30 Rock" for one episode this fall. The Emmy Award-winning actress will play free-spirited, 'Fatal Attraction'-like stalker Claire Harper. Claire is a former roommate of Liz Lemon's (Tina Fey) from Chicago who turns up in New York and begins to stalk Jack Donaghy (Alec Baldwin).

Last week, ET reported that the former "Friends" star would return to NBC for a guest appearance on the Emmy Award-winning comedy.

"Jennifer is not only incredibly lovely to have around, she also has what the young people would call 'mad skills.' We're very excited that she's joining us," says Tina in her several roles as creator, executive producer and star of "30 Rock."

The announcement that Jennifer would return to NBC was made by Teri Weinberg, executive vice president, NBC Entertainment, who said: "What a thrill to have Jennifer back on NBC on a Thursday night. She is the perfect comedic talent to work with the Emmy-winning '30 Rock' cast. This promises to be a memorable, hilarious night of comedy."

Aniston's last primetime acting turn was on Courteney Cox's FX series "Dirt."