Ididn't want the gig. ¶ The best new show on television, sure, but I was holding out for a real role, a solid guest-star part. I wanted, for instance, to die in a bed; or I wanted to watch, distraught, while somebody else died in a bed. I wanted a character with heft, range, arc. I had been a regular on a series -- granted, it was canceled after six episodes, but I had proved my mettle. ¶ I'll wait for something bigger, I told my manager -- I had a manager then -- and she told the casting director, and he told her to tell me not to be an ass; the "ER" role could recur. ¶ Three lines -- it didn't seem worth it -- but it wasn't like the offers were pouring in. I had been auditioning for Woman Jurist, Woman Reporter, Woman in Sales and, worst of all, just plain Woman. Meanwhile, here was a scene with a boy named Noah Wyle, and the lines, although there were only three, had some "umph." Plus, I had a name this time: not Woman but Shirley, Nurse Shirley to you.

I took the part. I got to the set. I was swathed in blue from head to toe, masked, hatted, gowned, gloved, goggled -- unrecognizable except for my voice ("Dinah, I heard you last night on "ER"!); maybe I did two episodes that first season; none at all the second. But then, the third, suddenly they were regularly writing me into the show; and after that, if they didn't, I wrote letters to ask if Shirley had retired or was I only on vacation -- in which case, I pleaded, bring me back, please bring me back, give me a last name and move me to the ER, where the nurses bared their faces more often than not.

Nothing doing, Shirley, said the writers. Once a surgical nurse, always a surgical nurse.

Still, each time I thought it was over, the call would come in: 80-something shows in 15 years; and occasionally, I even would have something fun to play. Mysterious though she was, there were clues to Shirley: She collected Buddy Holly records; she was married; she was prickly and irreverent and bossy; and her all-time favorite surgeon was Dr. Morgenstern (William H. Macy, that is) -- what good taste she had.

Shirley pushed the plot (and the gurneys) at worst; at best, she was comic relief, and either way, I took her seriously. One time -- we were shooting the 100th episode -- I entered and said my single line to Dr. Benton, informing him with the teeniest bit of attitude that he had people waiting for him in his office.

"CUT!" interrupted the director, a theatrical presence with a strong mid-Atlantic lilt. Out he came into the hall to whisper in my ear: "I think that was a bit judgmental, don't you?"

Yes, it was judgmental! I was acting! The scene was all about me; you didn't get that?

"Know your lines and don't bump into the furniture," advised Spencer Tracy. But how to spend eight to 10 hours on a set and not do what I had been trained to do? I worked my formidable brows above my mask, reacted to every line whether or not I was on camera, believed and hoped, until I didn't anymore -- until I realized I wouldn't be discovered on "ER." After that, I mostly kept my fingers crossed -- no close-ups, please. If my lines were covered in a two-shot or even the master, I might get home in time for supper with my family.

Still, periodically Shirley's surgical mask would come off, or I would get eight lines instead of five -- I'd joke then about how one of these days I'd take the scalpel into my own hands, à la Dustin Hoffman in "Tootsie."

One time, another actor saw through my shtick: "It won't happen," she said. "You achieve a certain status on this show, and that's where you stay."

In her tenure (not as long as mine), she went from guest-starring, to starring, to directing. So how could she have known about me? About Shirley? How did she know what I only pretended to accept?

Know your lines; don't bump into the furniture; get on with your life. And so I did. I played other roles, among them wife, mother, daughter, teacher, friend. Not that I ever took Shirley for granted, because I couldn't -- I didn't have a contract. But I stopped asking for a last name and a plot line of my own. Although I never stopped hoping for one more episode. Because it was a gig, not because I was invested. Or so I thought.

Saturday night, at the final wrap party, I was in decent spirits, having managed to slide an old black dress over my hips -- the same one I had worn to my first "ER" celebration a dozen years before. While my husband tucked into his plate at a table full of strangers, I stood at the bar -- carved from ice and consequently dripping all over my pointy black shoes -- and waited for a glass of wine. I scanned the room -- waved and grinned -- but it was all too easy to avoid the schmooze, and so began my unraveling. How strange that I didn't know these people any better than I had known them at the start.

Speeches, then a long reel of moments to remember. Cast photos, finally, with a cake as big as a California king. Somewhere in the middle of a photo, it hit me -- this was the very last time I would wonder if I should step up for the cameras with the rest; if I should take pains to shake the producer's hand; if I should bother to find the writers who regularly had given me work; if any of that would inform my future in any way.

I was suddenly undone -- sad, and sorry it was over -- having mostly to do with how little it finally meant to me, I thought. What did that say about who I was, who I wanted to be and how it all turned out?

I held it together until we got in the car, and then I cried all the way home. Who was I kidding to think I wasn't attached? For although my real life had unfurled worlds away from Stage 3 on the Warner Bros. lot, and although I seemed to have taken not a single real relationship with me, at long last, I had lost Shirley. Shirley, whom I hardly knew at all. Whom I knew, on the other hand, almost as well as I know myself.

Dinah Lenney, author of "Bigger Than Life: A Murder, a Memoir," most recently played a man on "Terminator: The Sarah Connor Chronicles." She wrote this article for the Los Angeles Times.