FOR someone whose only acting experience was playing a Boy George lookalike in a high school production of the musical “The Wedding Singer,” Harmony Santana is having an incredible year. Ms. Santana is making her big-screen debut in Rashaad Ernesto Green’s coming-out drama “Gun Hill Road,” which had its premiere in January at the Sundance Film Festival. Last month the movie made a splash on the gay film-festival circuit, opening Outfest in Los Angeles and closing Newfest in New York. It opens commercially in New York on Aug. 5.

But when Ms. Santana goes to sleep at night she does so not as a buzzed-about young starlet but as a resident of Green Chimneys, a group home in Harlem mainly for gay, lesbian, bisexual and transgender youth. Ms. Santana, who says she is in her early 20s, has been living full time as a woman only since last year.

She is the latest performer to join the tiny pool of openly transgender actors who are finding a place on screen. Her small cohort includes Candis Cayne, who appeared in the film “Stonewall” and the television series “Dirty Sexy Money,” and Laverne Cox, a reality-television star with a role in the coming Susan Seidelman film “Musical Chairs.” The most recognizable female-to-male personality today is probably Chaz Bono, the child of Cher and Sonny Bono who, while not an actor, is the subject of the documentary “Becoming Chaz.”