Ling -- the overbearing, litigious client on "Ally McBeal" -- will be causing a ruckus on a regular basis now that the actress who plays her, Lucy Liu, has officially joined the cast. Liu has guest-starred twice, once suing a Howard Stern-like shock jock for sexual harassment and later a plastic surgeon over a breast-implant operation. With so many strong-willed women (Calista Flockhart, Courtney Thorne Smith, Lisa Nicole Carson) already on "Ally," does the series really need another one? "It's always good to have strong supporting characters like hers," says TV analyst Marc Berman. "She can add a lot to the show, as long as Fox doesn't overexpose her."

Liu joins a storied line of actors who have been upgraded from guest-star to regular cast member. "The classic example is Urkel (Jaleel White)," says Berman. "He was a onetime-only guest star on 'Family Matters' as the next-door neighbor. The audience went wild about him, and the producers signed him up immediately full-time." Other actors to land a regular job on a Fox show after a guest stint include Jennifer Love Hewitt ("Party of Five") and Heather Locklear ("Melrose Place").