Soon after appearing in the original Broadway production of “Fiddler on the Roof,” she began a new career as a prominent casting director.Joanna Merlin, who, after originating the role of Tzeitel, the eldest daughter, in the hit Broadway musical “Fiddler on the Roof,” became a renowned casting director, notably for Stephen Sondheim musicals including “Into the Woods” and “Follies,” died on Oct. 15 at her younger daughter’s home in Los Angeles. She was 92.Her older daughter, Rachel Dretzin, said the cause was complications of myelodysplastic syndrome, a bone marrow disease.The idea of becoming a casting director came from Hal Prince, the powerful producer of “Fiddler,” after she had left “Fiddler” to raise her two young daughters. He had interviewed several candidates and told Ms. Merlin that most of them “just didn’t like actors,” she told Backstage magazine.“He felt that since I was an actor and a mother, that I might be a good choice,” she added. “He understood that I was raising children and told me that he didn’t care what hours I put in, just as long as I got the work done.”She set to work in 1970, casting replacement actors in “Fiddler” during its last two years on Broadway. For the next two decades, she cast six musicals that were composed by Sondheim and produced (and usually directed) by Mr. Prince on Broadway: “Company,” “Follies,” “A Little Night Music,” “Pacific Overtures,” “Side by Side by Sondheim” and “Merrily We Roll Along.”From left, Ms. Merlin, the composer-lyricist Stephen Sondheim, the director Harold Prince and the playwright George Furth during a casting session for the 1981 Broadway musical “Merrily We Roll Along.”Martha Swope/The New York Public Library for the Performing ArtsHer casting credits also include two other Sondheim musicals, “Sweeney Todd” and “Into the Woods”; Andrew Lloyd Webber and Tim Rice’s “Evita”; and “On the Twentieth Century,” by Betty Comden, Adolph Green and Cy Coleman. All those shows except “Into the Woods” were directed by Mr. Prince.“What I found so interesting with Joanna,” James Lapine, who directed “Into the Woods” and wrote its book, based on the Grimm brothers’ fairy tales, said in a phone interview, “was her determination to pursue nontraditional casting in the theater, which for me, at a young age, was something I hadn’t thought much about.”Ms. Merlin’s pursuit of diverse casting led Mr. Lapine to choose a Black actress, Terry Burrell, to replace the white one who had played one of Cinderella’s evil stepsisters, and Phylicia Rashad, who is Black, as a replacement for Bernadette Peters in the leading role of the Witch.In 1986, Ms. Merlin was a founder of the Non-Traditional Casting Project (now the Alliance for Inclusion in the Arts), which seeks more opportunities for actors of color and actors with disabilities.Ms. Merlin, noting that there were many talented, nonwhite actors, told The Record of Hackensack, N.J., in 1990. “The reason they should be cast is because they’re good,”Ms. Merlin also cast six films, including Bernardo Bertolucci’s “The Last Emperor” (1987), for which she won the Casting Society of America’s Artios Award. She also won an Artios for “Into the Woods.”Ms. Merlin, far right, with Zero Mostel, center, and three other “Fiddler on the Roof” cast members (from left, Maria Karnilova, Tanya Everett and Julia Migenes) backstage after the show’s opening night in 1964. Associated PressJo Ann Dolores Ratner was born on July 15, 1931, in Chicago. Her parents were Russian immigrants: Her father, Harry, owned a grocery store, and her mother, Toni (Merlin) Ratner, helped in the store and became a sculptor in her 60s.She moved to Los Angeles with her parents and her sister when she was 15.She attended the University of California, Los Angeles, for a year in the early 1950s and, after acting in plays in the Los Angeles area in the early and mid-1950s, appeared in her first movie role, a small part in Cecil B. DeMille’s “The Ten Commandments” (1956).After some more screen work and roles in Off and Off Off Broadway plays, Ms. Merlin made her Broadway debut in 1961 in Jean Anouilh’s “Becket,” as Gwendolen, the mistress of Thomas Becket, one of Britain’s most powerful figures in the 12th century, who was played by Laurence Olivier. Later that year, she returned to Broadway to portray Sigmund Freud’s wife in Henry Denker’s “A Far Country.”After four unsuccessful auditions for a role in Bertolt Brecht’s “Mother Courage and Her Children,” which was staged by Jerome Robbins, she auditioned eight times for Mr. Robbins when he was casting “Fiddler on the Roof,” which opened in 1964. Although she lacked a strong singing voice, she was cast as Tzeitel, the oldest daughter of Tevye the milkman, the show’s principal character.The syndicated columnist Leonard Lyons wrote that when Ms. Merlin was pregnant in 1965 with her daughter Rachel, Zero Mostel, who played Tevye, told the stage manager: “Joanna’s baby just kicked. Send baby a note — not to kick.”She left the show in 1965 after Rachel was born, returned as Tzeitel a year later, and departed again in 1967 when she was replaced by her understudy, Bette Midler (who was also Rachel’s babysitter). After Julie’s birth in 1968, Mr. Prince made his offer.She continued to act, mostly in films and on television. Her roles included the dance teacher in “Fame” (1980), Julia Roberts’s mother in “Mystic Pizza” (1988) and an old Jewish woman in a short film, “Beautiful Hills of Brooklyn” (2008), which she and Ragnar Freidank adapted from a one-woman play by Ellen Cassedy.TV viewers might be most familiar with Ms. Merlin’s recurring role in “Law & Order: Special Victims Unit.” She played Judge Lena Petrovsky 43 times from 2000 to 2011. No other actor has played a jurist more often in the “Law & Order” franchise. She also appeared, as two different defense lawyers, in five episodes of “Law & Order.”Ms. Merlin as a lawyer in a 1994 episode of “Law & Order.” She also played a judge in 43 episodes of “Law & Order: Special Victims Unit,” setting a record for the franchise.Jessica Burstein/NBCUniversal, via Getty ImagesHer career as an acting teacher began in 1998 at New York University’s Tisch School of the Arts, and a year later she began holding workshops dedicated to the acting technique of her teacher, Michael Chekhov.In the foreword to her book, “Auditioning: An Actor-Friendly Guide” (2001), Mr. Prince wrote: “Her taste is impeccable. In no instance can I remember her recommending anyone less than interesting for a role.”In addition to her daughter Rachel, a documentary filmmaker, and her daughter Julie Dretzin, an actress, Ms. Merlin is survived by five grandchildren. Her first marriage, to Marty Lubner, ended in divorce. Her marriage to David Dretzin ended with his death in 2006 after a car accident in which he suffered a traumatic brain injury. Her sister, Harriet Glickman, died in 2020.For “Pacific Overtures,” which takes place in Japan after Commodore Matthew C. Perry’s visit in 1853 and which had an all-Asian cast, Ms. Merlin engaged in “what may be one of the most poignant talent searches undertaken for a Broadway show,” according to a 1976 article in The New York Times.Racism and economics often forced Asian actors out of the profession at the time. So when she had no luck finding actors in New York, she worked with Asian community and theater groups, Asian newspapers and the State Department to fill the roles. A third of those ultimately signed for the production were nonprofessionals.Among them was the actor Gedde Watanabe, who was a young street singer in San Francisco when she approached him and invited him to audition.“I didn’t believe her,” Mr. Watanabe said. More