Gus made his impromptu debut three years ago in the second act of Woolly Mammoth Theatre's production of "Life and Limb." It was a brief cameo appearance during a press performance, but it garnered a mention in the next day's reviews.

A brindled tabby cat, he already had become a fixture backstage at New Playwrights' Theatre, now The Church Street Theatre. Like any alley cat, his overtures were inevitably at his own discretion, and so were successive stage appearances, sauntering down the catwalk during a production of "Three Postcards" two seasons ago and leaping onto the stage and into the audience during a matinee last spring of "Faulkner's Bicycle."

Frequently only the audience noticed. "If I had seen Gus, I could have add-libbed that I looked like something the cat dragged in," mourned actress Brigid Cleary.

No one can explain why Gus decided to make this little theater in Northwest his home, considering all its struggles and metamorphoses, from New Playwrights' to American Playwrights to Church Street. But his glory days began about four years ago.

He had started coming around in 1984, when Jim Taylor, who didn't care for cats, was production manager. Gus would "run into the theater whenever the door was left open and hide underneath the stage, refusing to leave until chased with a broom handle," he said.

When Arthur Bartow left as New Playwrights' artistic director two years later, management shifted to cat lover Dan Kiernan, who welcomed Gus and treated him like theater family.

Soon Gus established the furnace room as his quarters and had full run of the theater. The exception was supposed to be during performances, when he usually took a stroll around the neighborhood.

"Most theaters don't allow pets because most theaters are governed by unions," Cheryl Svannack said last year when she was still American Playwrights Theatre's producing manager. "But we have a cat, which also exemplifies APT's community orientation. We are all willing to pitch in and take care of Gus . . . . Many is the morning we come in and there is no coffee for us, but there is always cat food for Gus."

In return, the runaway feline became everything from an audition prop to a set designer. When he left paw prints on a freshly painted set, designer William Kelley was ecstatic.

When he showed up at training sessions, artistic director Peter Frisch, the man behind the conversion of New Playwrights' to American Playwrights, used him as a tool. "A number of times he suddenly appeared on stage and I told the students to incorporate him into the scene . . . . If you're supposed to be living and breathing and it's happening fresh every minute, the sudden appearance of a cat provides the ideal opportunity for improvisation," he said.

Said actor Nick Olcott: "Gus has a better instinct for finding the best light and the best center on stage than most actors."

Today, Gus continues to serve the theater in its incarnation as a stage for book-ins, acting as companion for manager Edward McGee, the sole staff member and book-in agent.

"Gus functions as a paperweight for scripts in a drafty upstairs office as well as a body warmer on particularly cold days," he said.

He also has become something of a symbol for a Washington institution that has shown itself to possess as many lives as any cat. A true vagabond, the changing hands that feed him never phase him, as long as there's tuna in the dish by the door.

Barbara Gross worked as a house manager and in the theater box office from 1985 through 1989.