Although still largely unofficial, cast members apparently returning for the new series of Twin Peaks include:
Kyle McLachlan (Special Agent Dale Cooper) OFFICIAL
Ray Wise (Leland Palmer, despite being dead!)
Madchen Amick (Shelly Johnson)
Richard Beymer (Ben Horne)
Michael Ontkean (Sheriff Harry S Truman)
Peggy Lipton (Norma Jennings)
Sheryl Lee (Laura Palmer/Madeline Ferguson, despite both being dead!)
Dana Ashbrook (Bobby Briggs)
Grace Zabriskie (Sarah Palmer)
Michael Horse (Deputy Hawk)
Catherine E Coulson (The Log Lady)