She helped Laura Dern, Marlo Thomas, Mickey Rourke and many others overcome fears, find their characters and discover “the joy of acting.”Sandra Seacat, who had a modest career as an actress and a formidable one as an acting coach, putting her own spin on techniques she had learned under Lee Strasberg at the Actors Studio to help Laura Dern, Marlo Thomas, Mickey Rourke and numerous other stars achieve some of their best performances, died on Jan. 17 in Santa Monica, Calif. She was 86.Her husband, Thurn Hoffman, said the cause was primary biliary cholangitis, an autoimmune disease.Ms. Seacat joined the Actors Studio in the early 1960s, when Mr. Strasberg was the artistic director and imparting the rehearsal and acting techniques often called simply the Method. Before long she began leading classes, and her reputation as an acting coach started to grow.By the early 1980s she was applying the psychiatrist Carl Jung’s theories about dreams and the unconscious to her coaching, helping students use their dreams to illuminate their own feelings and the characters they were developing, a technique called “dream work.”“The artist is a shaman, a wounded healer,” Ms. Seacat said in a 2015 video interview with The Hollywood Reporter. “We have wounds that we want to bring forth through the material. It’s joyful, it’s painful, but not painful in a bad way. And when you do that you also heal people in the audience.”Actors who worked with her echoed that sense.“The work was our bond,” Marlo Thomas, for whom Ms. Seacat was a coach, teacher and mentor for more than 40 years, said by email. “She taught me to seek the truth in myself, to heal my wounds and those of the audience. She changed me as a human being, teaching me to cast off my protective armor and see the world as a baby might see it, feeling and experiencing it for the first time.”Ms. Thomas’s career had for years been defined by her role in the 1960s sitcom “That Girl,” but Ms. Seacat helped her branch out, leading to more substantial parts and an Emmy Award for outstanding lead actress for her role as a woman who had spent years in a mental institution in the television movie “Nobody’s Child” (1986).Peggy Lipton had also achieved some 1960s TV fame, as one of the stars of the crime show “The Mod Squad,” but she then stepped away from acting for years to raise her children. By the late 1980s she was thinking about returning, but, she told The Los Angeles Times in 1993, “it was very scary.”She joined one of Ms. Seacat’s classes, nervous at first. “I used to sit under the table near the door,” she said, “so if she ever called on me I could get out.”But, she said, Ms. Seacat eventually helped her break through the fear. Ms. Lipton, who died in 2019, went on to accumulate dozens more TV and film credits, most memorably as the diner owner Norma Jennings on the trendy series “Twin Peaks” and its sequels.Mickey Rourke had done little acting — he had been an amateur boxer — before he arrived in New York in the 1970s and eventually began working with Ms. Seacat. He has often credited her with helping him to get serious about the craft of acting, leading to attention-getting roles in the 1980s in “Body Heat,” “Rumble Fish,” “Angel Heart” and other movies. She was responsible for “channeling all it was that was messing me up into something creative and challenging,” he told The Los Angeles Times in 1984.Younger stars also benefited from her coaching, among them Andrew Garfield, who played the title character in “The Amazing Spider-Man” (2012) and its sequel and earned an Emmy nomination for his lead role in the mini-series “Under the Banner of Heaven” last year (in which Ms. Seacat played his character’s mother).“She was a revolutionary, a culture-changing teacher of acting and storytelling,” Mr. Garfield said in a statement. “She is a beacon for all of us of what a life of deep meaning and beauty can look like.”Ms. Seacat and the actress Laura Dern in an undated photo. “Sandra gave me the greatest gift an actor could ever ask for,” Ms. Dern said. “Sandra gave me the joy of acting.”Katie Jones/Variety, via Penske Media, via Getty ImagesSandra Diane Seacat was born on Oct. 2, 1936, in Greensburg, Kan., in the midst of the Dust Bowl, to Russell and Lois (Cronic) Seacat.After graduating from Northwestern University, Ms. Seacat moved to New York and began her acting career. In 1959 she married Arthur Kaufman, and some of her early credits are under the name Sandra Kaufman.Once she was admitted to the Actors Studio — she said she auditioned while pregnant — she appeared in various productions, including “Three Sisters” on Broadway in 1964, in which she had a small role. She had small roles in two other Broadway productions as well, “A Streetcar Named Desire” in 1973 and “Sly Fox” in 1976.Ms. Seacat also took occasional roles on television and in films throughout her career. She directed one feature film, the 1990 comedy “In the Spirit,” which had a star-studded cast that included Ms. Thomas, Olympia Dukakis, Elaine May, Melanie Griffith and Peter Falk.“‘In the Spirit’ is a flat-out New York comedy, with all of the pluses and minuses that go with that territory,” Bob Strauss wrote in his review in The Los Angeles Daily News. “Director Sandra Seacat, one of the industry’s most respected acting coaches, lets her cast get away with Method murder. But the performers’ mannered joy is also infectious; even when the jokes don’t work, you smile along just to feel part of the party.”Ms. Seacat’s marriage to Mr. Kaufman ended in divorce, as did her marriage to Michael Ebert. She married Mr. Hoffman in 1982. In addition to him, she is survived by a daughter from her first marriage, Greta, and a sister, Serena Seacat.The long list of other stars Ms. Seacat worked with includes Jessica Lange, Rachel Ward, Ryan Gosling and Laura Dern.“Sandra gave me the greatest gift an actor could ever ask for, which was beyond a method or a craft or anything anybody talks about,” Ms. Dern said in the 2015 Hollywood Reporter video. “Sandra gave me the joy of acting.” More