Robin Weigert is best known for her role as Calamity Jane in the HBO series Deadwood, for which she received a 2004 Emmy Award nomination for Best Supporting Actress in a Drama Series. She appeared previously on HBO as the Mormon Mother in the Golden Globe-winning Angels in America, directed by Mike Nichols, and starring Meryl Streep, Al Pacino and Emma Thompson. Robin was featured in the films The Sleepytime Gal, Loggerheads and Reservations, due out next year. Upcoming films also include Steven Soderbergh's The Good German, starring George Clooney and Cate Blanchett and Things We Lost in the Fire, starring Benicio del Toro and Halle Berry. Robin has guested on numerous shows including, most recently, Lost, Law and Order:SVU, The Unit and Cold Case. Almost all of these on camera credits were accumulated starting in 2003. In honor of her having seemed to appear out of nowhere, Robin was a recipient of the 2005 Breakthrough of the Year Award from Hollywood Life Magazine.

Before moving to Los Angeles, Robin enjoyed an almost decade long stage career in New York. Most recently on Broadway as Poppy Norton-Taylor in the hit revival Noises Off, she was nominated for Drama Desk and Lucille Lortel awards for her acclaimed turn in Richard Nelson's Madame Melville, with Joely Richardson and Macaulay Culkin. Mike Nichols saw her in Melville and, due to a scheduling conflict, asked her to step in for Marcia Gay Harden in the role of Masha in 2001's hot-ticket event, The Seagull in Central Park, with a cast that included Meryl Streep, Kevin Kline, Natalie Portman, Phillip Seymour Hoffman and Christopher Walken. What followed was Nichols' Angels in America which opened a door at HBO and helped pave the way for Deadwood, but before this Robin was working for years in the theater, on Broadway in Lincoln Center's Twelfth Night, off-Broadway in A place at the Table (MCC), Arms and the Man (The Roundabout), Hamlet (The Public), Goodnight Children Everywhere (Playwrights Horizons), Pride's Crossing (Lincoln Center), off-off-Broadway in Dogg's Hamlet, Cahoot's Macbeth and The Three Sisters and regionally at McCarter, Arena Stage, Long Wharf, New York Stage and Film, A.C.T. and the Berkshire Theater Festival. It gave her great pleasure to return to A.C.T. between seasons two and three of Deadwood to play the role of Josie in O'Neil's A Moon for the Misbegotten, for which she received a Theatre Critics Circle Award.

Robin received her MFA in acting from NYU.