Tina Fey, Mariska Hargitay Tina Fey, Mariska Hargitay

Mark your calendars: NBC has announced its season-finale dates — and the airdate for 30 Rock's 100th episode.

Fall TV scorecard: Which shows are returning? Which aren't?

The sitcom's triple-digit milestone will air Thursday, April 21 as a one-hour episode. The hour will find TGS dealing with the prospect that its 100th episode could be its last.30 Rock's fifth-season finale will air Thursday, May 5, the same night as Perfect Couples' closer.Check out NBC's full list of season finales: Monday, April 4Harry's Law, 10/9cFriday, April 8Who Do You Think You Are?, 8/7cTuesday, April 19Parenthood, 10/9cSunday, May 1America's Next Great Restaurant, 8/7cThursday, May 5Perfect Couples, 8:30/7:30c30 Rock, 10/9cThursday, May 12Community, 8/7c (one-hour finale)Outsourced, 10:30/9:30cMonday, May 16Chuck, 8/7c Wednesday, May 18Law & Order: Special Victims Unit, 10/9cThursday, May 19The Office, 9/8c (one-hour finale)Parks and Recreation, 10/9c (one-hour finale)Saturday, May 21Saturday Night Live, 11:30/10:30cSunday, May 22The Celebrity Apprentice, 9/8cMonday, May 23The Event, 9/8cTuesday, May 24The Biggest Loser, 9/8c