''ER,'' ''Beverly Hills, 90210,'' and ''Melrose Place'' are among the shows to bring on new characters this season

WHO AND WHERE: ALEX KINGSTON: British thespian (Masterpiece Theatre’s Moll Flanders) and soon-to-be ex-wife of Ralph Fiennes — scrubs in on ER.
JOB DESCRIPTION: As new surgical resident Dr. Elizabeth Corday, she’ll spar with Eriq La Salle’s Dr. Benton (doesn’t everyone?).
THE LOWDOWN: ”She enjoys good, healthy competition,” says executive producer Lydia Woodward. ”But it won’t be bitter or hostile between her and Benton. It will be much more fun.”

WHO AND WHERE: After being introduced as Dr. Anna Del Amico last season, MARIA BELLO, star of Mr. & Mrs. Smith, will join ER‘s staff permanently.
JOB DESCRIPTION: The latest emergency-room resident will work most closely with Dr. Carter (Noah Wyle).
THE LOWDOWN: ”Carter and Del Amico will bond pretty quickly and easily,” says Woodward. But, she adds, watch out for ”disagreements later.”

WHO AND WHERE: MARTIN MULL, Roseanne‘s gay nemesis on her defunct series, joins Sabrina as Vice Principal Kraft.
JOB DESCRIPTION: When not puzzling out what’s so strange about Sabrina (Melissa Joan Hart), he’ll be pining for Aunt Hilda (Caroline Rhea), who, alas, sees no magic in him.
THE LOWDOWN: ”We felt we needed more male presence,” says executive producer Paula Hart. ”And Martin’s the funniest man walking the face of the earth.”

WHO AND WHERE: HILARY SWANK, best known for her fancy footwork in The Next Karate Kid, joins Beverly Hills, 90210 as Carly Reynolds.
JOB DESCRIPTION: Single mom Carly will bewitch Steve (Ian Ziering), while no doubt serving as a warning to virgin-no-more Donna (Tori Spelling) about premarital sex.
THE LOWDOWN: ”I don’t know her too well yet,” says costar and executive producer Jason Priestley. ”But judging from her movie, I’m sure she’ll kick butt.”

WHO AND WHERE: Former Miller beer hunk VINCENT YOUNG moves into the 90210 zip code as Noah Hunter.
JOB DESCRIPTION: Valerie’s (Tiffani-Amber Thiessen) new boy toy will live on the Martins’ yacht — and fill the elusive-guy void left by Dylan McKay’s (Luke Perry) exit.
THE LOWDOWN: ”It’s going to take us a while to figure out what Noah’s deal is,” says Priestley. ”He’s sort of our international man of mystery.”

WHO AND WHERE: Daytime soap star (Loving) LINDEN ASHBY joins prime-time sudser Melrose Place as Dr. Allan ”Coop” Cooper.
JOB DESCRIPTION: Upset by Kimberly’s death, he moves to L.A. to torment Michael (Thomas Calabro). Despite living in Matt’s old pad, producers vow Coop’ll have a sex life.
THE LOWDOWN: ”He’s more moral and a better physician than Michael or Peter,” says exec producer Frank South. ”We had to do something, or the AMA was going to attack us for defamation of doctors.”