When Deirdre O’Connell returned to work two days after winning this year’s Tony Award for best performance by a leading actress in a play, the production staff of her current show, “Corsicana” at Playwrights Horizons, greeted her with a balloon arch and cake. O’Connell, 68, enjoyed it. For a little while, anyway. But “Corsicana,” a lonesome, oblique quartet by Will Arbery, is in previews. It begins press performances soon. O’Connell needed to rehearse. So she put the celebration aside.“I just went, ‘Well can’t think about that anymore,’” she said, later that same day. “I have to work.”Perhaps you saw last fall’s “Dana H.,” the show that won her the Tony, in which she spent a harrowing hour and change lip-syncing a woman’s recollections of her abduction by a white supremacist. Or maybe you have already caught “Corsicana,” in which she seems to unseal her character’s soul as casually as you or I uncap a beer. Or, at some point in the last four decades, you might have witnessed the performances that earned her Obies, Lucille Lortels, and a New York Drama Critics’ Circle Prize.O’Connell in “Dana H.,” lip-syncing and “brilliantly pulling off one of the strangest and most difficult challenges ever asked of an actor,” Jesse Green wrote in his review.Sara Krulwich/The New York TimesBut possibly you have never seen O’Connell onstage, so here is what I can tell you: She is an actress of rigor and possibility. She will abandon herself to a character without apology or vanity or self-preservation. Some actors are simply better at the business of being alive, at seeming to present life onstage, and she is one of them.Her absolute focus, Lucas Hnath, the “Dana H” playwright, told me, “creates an opening for something — call it life, call it the spirit. Something ineffable and wild rushes in to fill the space.”Or here is how Les Waters, the director of “Dana H.,” put it: “She is available to life.”O’Connell — Didi, to her intimates — is petite and nimble, with a queenly nimbus of red hair and a default expression, offstage anyway, of intent curiosity. She grew up in western Massachusetts, the granddaughter of a Ziegfeld girl and the daughter of Anne Ludlum, an actress and playwright. As a child, she was, as she put it, “a classic theater nerd,” shy and uncomfortable offstage. “And then strangely comfortable and excited” when performing, she said.Jamie Brewer, left, and O’Connell in the Will Arbery play “Corsicana,” now in previews at Playwrights Horizons.Sara Krulwich/The New York TimesAfter two years of college, she made her way to Boston, apprenticing with an experimental theater company there, and then joining others — in San Francisco, in Baltimore. That scene took a lot out of her. “I felt a little too vulnerable just having my life swallowed up by it,” she said, so in her mid 20s she moved to New York, determined to become what she called “a regular actress.” (Has anyone ever thought of O’Connell as “regular?”) Yet she carried experiment with her. Even in her most controlled performances — “Dana H.” among them — there is something feral, ungovernable at the heart.She spent the next five years pouring drinks, pouring coffee, learning how to audition, learning how to act. In her late 20s, right around the time she found the rent-stabilized East Village apartment (with a bathtub in the kitchen) where she still lives, she booked the national tour of John Pielmeier’s “Agnes of God.” Except for the five years she spent in Hollywood, amassing just enough jobs for a nest egg and a Screen Actors Guild pension, she has rarely been offstage since. Screen acting, it turns out, never gave her what she wanted, a feeling of un-self-consciousness, of surrendering to a role in a way that sounds a little like religion, a little like ego death.“I’m into the numinous experience,” O’Connell explained. “I’m into the thrills.”She hadn’t expected to win the Tony on Sunday night. With good reason. “Dana H.,” which required O’Connell to mouth along to prerecorded interviews with the playwright’s mother, demanding complete submission to the text and its rhythms, is more challenging than most Broadway fare. And it had closed in November, meaning that some Tony voters might already have forgotten it. Besides, three of the four women in her category (LaChanze, Ruth Negga and Mary-Louise Parker) are far better known.O’Connell had watched the Tonys for decades, once in person, but much more often at home, in that same rent-stabilized apartment that she shares with her partner, Alan Metzger, an educator. She knew that at the moment an award is announced, everyone stares at the losers. So as the Tonys entered its final hour, she prepared herself.“I was ready to be so awesome and classy,” O’Connell recalled.But she didn’t lose. And so O’Connell, who had appeared on Broadway only twice before, found herself walking up the aisle of the Radio City Music Hall, in a black jumpsuit from Rent the Runway. On that jumpsuit: “I thought it was going to be a little more Cinderella, but then I was like, I guess not, I guess I’m old,” she said. (None of the designers her producers contacted offered to dress her. Their loss.)O’Connell in her dressing room at Playwrights Horizons. “There should be a pamphlet that helps people get through the days after,” she said of the post-win experience. “You really don’t know how to behave.”An Rong Xu for The New York TimesA person could argue that this award was the culminating moment of a nearly five-decade career. And yet, O’Connell — who looked awesome, classy and indisputably shocked — used her 90 seconds of speech time to look forward, manifesting the theatrical future she hopes to see.Holding her statuette, she said, “Please let me standing here be a little sign to you from the universe to make the weird art.”After receiving the award, a golf cart shunted her to one press room, then another. The ceremony had ended by then. She had left her purse at her seat when she walked onstage. “What New Yorker walks away from their keys and their phone?” she said. Still, she managed to reunite with Metzger, and they attended an after-party at the Plaza and a second one at the Omni and then it was after 3 a.m. and she was in a car, heading back to that bathtub in the kitchen.The next day, Monday, she slept late and then read through congratulatory texts and emails, too many to ever answer. Washing dishes, she suddenly felt devastated that she hadn’t thanked Metzger in her speech; she had felt too reluctant to reveal any of her private life. Which is to say, there were a lot of feelings, most of them good.“There should be a pamphlet that helps people get through the days after,” she said of the post-win experience. “Because you’re so suddenly shot out of a cannon, and you really don’t know how to behave.”On Tuesday, after cake, she spent some hours rehearsing the role of Justice, a librarian, an anarchist, a would-be lover, a friend. Sam Gold, the director of “Corsicana,” who in an email noted both her “free and open energy” and her extreme technical precision, gave her notes. She catnapped. Then she performed — baring her character’s soul, without showiness or fuss.“I like the excavating of finding another person inside me,” she said of her process.After bows, she changed her clothes and tidied up. Just past 10 p.m., she emerged into the fetid air of Hell’s Kitchen, greeted a few friends and fans, and went to find a restaurant that was still open.Even offstage, over a mediocre dinner at a sidewalk table on a block that smelled of sewage, it was something fine and rare to be held in her attention, to be, for a moment, her collaborator.This, anyway, has been Arbery’s experience. “It almost feels a little unfair to get to work with someone so good,” he told me.She marveled that she had been able to keep going for typically long hours, at typically low pay, for all of these years. That cheap apartment helped, she said. As did the fact that she has no children, though she is close to Metzger’s. The Tony could have come to her earlier. “I could have taken it at 48. I could have used it,” she said. But she has never felt that she missed out on much. The numinous experience, the thrills, they have always been near at hand. And she is happy to have received the prize now.“I certainly didn’t think that it was going happen this way,” she said. “It wasn’t a plan. But it’s pretty sweet.” More