NO MATTER WHAT PLAY HE APPEARS in, roguish British actor Nicol Williamson is always a show-stopper in himself. He once threw beer in producer David Merrick's face and then punched him for firing an actor friend. During a curtain call in 1976, he slapped a chorus member for talking. At times he has stopped his performance while latecomers took their seats, and shouted at audiences he thought weren't paying attention.

Now Williamson, 52, is once again railing against a sea of troubles. During a dueling scene in the first act of the Broadway comedy hill Hate Hamlet, he whacked costar Evan Handler with the flat of his sword, leaving a six-inch bruise on Handler's right buttock. Furious, Handler stormed offstage and quit the show. "Well? Should I sing?" Williamson asked a stunned audience. "It seems someone who has missed a few parries has elected to leave the stage, which, unless one is very, very sick, is an unprofessional thing to do."

Aye, there's the rub. During a 1969 performance of his acclaimed Hamlet in Boston, Williamson himself stalked off in midscene, muttering, "I can't go on. I'm played out." He returned 20 minutes later, apologized to the audience and finished the play.

Handler, 28, who was replaced in the show by understudy Andrew Mutnick, was less contrite. "I was purposely assaulted with a sword," says the actor, adding that the blow was only the latest of the slings and arrows that Williamson, who plays the ghost of actor John Barrymore, had inflicted on him and other cast members. Among their complaints: Williamson made onstage remarks about their acting and publicly criticized the play's quality. Playwright Paul Rudnick says he learned one thing from the flap. "In my next play," he says, "instead of swords, I'm going to use cream pies."