Have you a New Year's Eve party to attend? If not, several New Jersey theaters are throwing some big bashes on Sunday night - and everyone's invited.

Such as The New Year's Eve Celebration that the Paper Mill Playhouse will present. The Millburn theater knows that you may very well have been invited to a party, but you don't want to get there too early. No problem: It's scheduled a 7 p.m. show, which will get you to wherever you're going well in time to sing ''Auld Lang Syne.'' On the other hand, if you don't have to be anywhere by midnight, Paper Mill is providing a second show starting at 10 p.m.

Whichever performance of The New Year's Eve Celebration you attend, you'll be reacquainted with many Paper Mill performers from the recent past: Michael Gruber, whom we saw Singin' in the Rain; Stephanie Pope, the Folies Bergeres vixen in Nine, and, of course, the theater's artistic director Robert Johanson, who's played everything at the Playhouse from a boy who could fly to a man who could walk on water.

Also on hand will be the performer who'll always be the answer to the trivia question, "Who was the leading man of the first show Paper Mill produced at its new, post-fire playhouse?" Answer: Mark Jacoby, who in 1980 played Browning in the musical saga of Robert and Elizabeth. More recently, though, he was seen starring on Broadway in Show Boat.

Other alumni include Alton Fitzgerald White, Angela Robinson, LaTonya Holmes and Sharon Wilkins, recently in Dreamgirls; Charles Repole, a Tony-nominated actor for Very Good, Eddie before he became a director, as you'll see next week with his production of You Never Know, and Judy McLane, who did so well in Oliver! and will portray 'Evita' at the Playhouse come June.

The evening will feature two other stars who'll soon be trodding Paper Mill's boards: Clint Holmes, preparing to headline his own new musical, Comfortable Shoes (Feb. 14-March 24), and Tony winner Leslie Uggams, who'll take on the Ethel Merman role in Irving Berlin's Call Me Madam (April 3-May 26).

Orchestra seats to The New Year's Celebration are $60, while mezzanine are $50. The Paper Mill Playhouse is on Brookside Drive in Millburn. Call (201) 376-4343.