After playing every conceivable type of movie villain, a forlorn lover in 1983's Terms of Endearment, and several psychotics in 1992's Raising Cain, John Lithgow was ready to lighten up. So when the husband-and-wife team of Bonnie and Terry Turner (former Saturday Night Live writers) approached him with 3rd Rock From the Sun, it didn't take long for the two-time Academy Award nominee to agree to risk the final frontier of character acting the situation comedy.
Much to NBC's delight, 23 million people took that risk with Lithgow, checking out 3rd Rock when it premiered Jan. 9 (a fact the network touts in numerous ''Must-See TV'' ads). Lithgow plays the pompous-yet-endearing High Commander of a group of aliens posing as humans to study earthling behavior. ''It's more like science farce,'' says Lithgow. ''I hadn't done comedy in years. And you really can't do physical comedy in movies anymore.'' Or the kind of legal overacting normally found on stage, where Lithgow got his start. ''This is a character who has downloaded all of Earth's knowledge. I don't flatter myself by saying I know everything, but I've got a great flair with theatrical skills, and it's wonderful to have one performance where I can trot them all out.''
And trot he does: Lithgow struts his stuff in squeaky-tight leather pants, tangos a la Charo (complete with hootchie-cootchie sound effects), and gets his human unmentionables stuck in his zipper. But 3rd Rock's physical humor goes beyond slapstick, edging into adolescence with a series of mammary-oriented one-liners (e.g., ''Check out the yabos on Miss Tunisia''). While NBC recently slapped itself on the wrist for the sitcom's ''body-part humor,'' Lithgow refuses to blush. ''The jokes bounce back and forth between the brain and the groin, pausing now and then at the heart,'' says the Harvard graduate. ''Intellectual humor is all well and good, but people laugh harder at dirty jokes.''
As long as the viewers keep laughing, Lithgow is prepared to exchange the ''lazy'' pace of moviemaking for the frantic world of television. Still, 3rd Rock's Friends-size premiere audience made the actor a little nervous. ''In a way, I was afraid of it succeeding,'' he says. ''I've always had a sort of innate fear of becoming too well known in any one role. I'm a character actor, and the fun of that is being different every time.'' Needless to say, should ratings demand it, the dutiful thespian will oblige with a five-year-or-more commitment. ''So far I've done 13 episodes and I never tired of it,'' says Lithgow. ''But people may get awfully tired of me.''