Born in Washington, D.C., Weigert studied drama, and after earning a Master’s of Fine Arts degree in acting, she built up a body of stage work, including “Madame Melville,” for which she earned nominations from both The Drama Desk and Lucille Lorte awards. In 2001 she played the part of Masha in the popular Central Park play “The Seagull,” directed by Mike Nichols and starring Meryl Streep and Kevin Kline. Nichols was so impressed with her work that he cast her in the highly acclaimed “Angels in America” on HBO, where she played Mormon Mother, in 2003.
Drawing further acclaim on stage for her peformance as Poppy Norton Taylor in “Noises Off,” Weigert also appeared in numerous TV shows, including “Law & Order” on NBC and “Without a Trace,” “Judging Amy” and “Cold Case,” and was seen in the films "Sleepytime Gal" (2001), "Two Weeks Notice" (2002) and the straight-to-video "What I Came For" (2004). But it was "Deadwood" that made her a favorite with audiences and critics alike. As portrayed by Weigert, Calamity Jane lives up to her name and reputation as being as infamous, if not just as tough, as Wild Bill Hickock, played on the show by Keith Carradine, drinking and slugging it out with the best and worst of the men on the show, whenever she dropped into town. For her performance, she was nominated for an Emmy for Best Supporting Actress in a Drama Series in 2004.
She was next cast in the Steven Soderbergh-directed “The Good German, with George Clooney, which followed an American correspondent who returns to Berlin soon after Hitler's defeat. There to write about the Allied triumph and search for his lost love, he stumbles upon a murder mystery involving an American soldier (lensed 2005).