By PATRICIA O'HAIRE

The senior Broadway cat is about to take her last meow.

For the past 18 years, eight times a week, Marlene Danielle, the last remaining actress from the original cast of "Cats," has looked into a mirror backstage at the Winter Garden Theater and begun the process of morphing herself, whisker by whisker, into a Practical Cat named Bombalurina.

That routine ends Sunday, when "Cats," the longest-running show ever to play on Broadway, takes its final curtain call. Marlene was in it when it opened on Oct. 7, 1982, and she'll still be in it when it closes. Not until then will she turn in the skintight red-and-black costume and wild-looking yak-hair wig she's worn all these years.

After 18 years singing the same songs, making the same dance moves, hasn't she ever been bored?

Her answer is a quick, firm "No."

In a profession hardly noted for long-term employment, Danielle's story is unique. Petite, bright-eyed and animated, she began in "Cats" as an understudy, was promoted to a featured role, then moved into the larger part of Bombalurina. Her work has bought her a home in New Jersey and a farm in Pennsylvania, paid for the restoration of both, and left enough over to feed her family and her own cats — 10 of them. Her son was 7 when she joined the show. He's 25 now and filming a documentary about the final days of "Cats."

Danielle, who's divorced, grew up in Greenwich Village and now lives just across the river, in Jersey City. Though she originally wanted to be a singer, she ended up a dancer, and that's what's kept her busy most of her professional life. She was on Broadway in the "West Side Story" revival, then Off-Broadway in "Little Shop of Horrors."

"I auditioned for lots of shows when that closed, including 'Cats,' but didn't get hired," she said. "I remember I had just got home after collecting my last unemployment check when the phone rang. It was the 'Cats' company saying there was a spot for me in the show — understudying four roles.

"I hung up and went 'E-E-E-E-E!' at the top of my lungs. I knew it would be a mega-musical, and I knew I wanted to be part of it. And I still am!"

Although about 80 dancers have come and gone since she was hired, she has the same spot in the dressing room she had when she started; she and 11 other female cats share a long table filled with makeup, Kleenex, jewelry and the bits and pieces people collect. Marlene (named after Dietrich, whom her mother admired) has the second chair from the door. "I picked it out myself," she says. "I wanted to be near the door but not at it — there's always a lot of traffic in and out."

Any regrets? She thinks for a moment.

"One thing I'd have really liked to do was replace Chita Rivera in 'Kiss of the Spider Woman.' But they were looking for a name, and I wasn't one, so I was asked to be her understudy. But I couldn't see myself sitting around waiting to go on for a year or so. Especially considering Chita's work record — she never misses a show."

So what's next for this cat? "I don't fret and worry. Somehow things will work out. I've paid my dues. I think there's justice in the universe."