Nielsen grew up in the Washington, D.C. and Bethesda, Maryland areas, the daughter of Homer Nielsen, who was born in the Philippines, and Eloise Nielsen. Her mother, a Democrat, worked in government, at one point for president Jimmy Carter, and her father was a U.S Navy captain. Her sister was Karen Grammaticas, wife of Dr. Andrew Grammaticas. Her family spent summers at Cape Cod. Her paternal grandfather was Harold Nielsen, who fought in World War I and had Danish ancestry. Her great-grandfather, Lewis Gerard, was an immigrant from France who fought for the Union in the Civil War. She trained at Northwestern University and the Yale School of Drama. At Yale her classmates included Frances McDormand and Tony Shalhoub. She is married to actor Brent Langdon.
Career
Broadway
Nielsen has appeared in several Broadway shows. Her first appearance was in the 1985 production of The Iceman Cometh as Pearl. She next appeared in Jackie: An American Life playing various characters, including Rose Kennedy and Marilyn Monroe. In 2000 she played the role of Ninetta in a new production of The Green Bird. In 2005 she played Eunice Hubbell opposite Natasha Richardson's Blanche Dubois and Amy Ryan's Stella in A Streetcar Named Desire. In 2008 she played Madame de Volanges opposite Laura Linney as Marquise de Merteuil in Dangerous Liaisons and also played Anna in To Be or Not to Be. In 2010 she played The Storyteller in Bloody Bloody Andrew Jackson. She later appeared on Broadway in Christopher Durang's play Vanya and Sonia and Masha and Spike as Sonia. For this role, Nielsen was nominated for the 2013 Tony Award for Best Lead Actress in a Play. In 2014, she returned to Broadway, playing the role of Penny Sycamore in You Can't Take It with You. She played the role until the show closed on February 22, 2015, after 169 performances.
Off-Broadway
Nielsen has appeared in numerous Off-Broadway shows. She won an Obie Award for Best Actress for her role as Madeline Newell in Dog Opera. Nielsen won the Obie and a Drama Desk Award nomination for Best Featured Actress for her role as Mrs. Siezmagraff in Betty's Summer Vacation by Christopher Durang. Her first Off-Broadway appearance was in a 1984 New York Shakespeare Festival production of Henry V at the Delacorte Theater in which she played Mistress Quickly. In 1988 she appeared opposite Laura Dern in The Palace of Amateurs. In 2005, Nielsen starred as Veronica in Christopher Durang's play Miss Witherspoon at Playwrights Horizons. In 2007 she played the lead role of Mary in Crazy Mary by A. R. Gurney at Playwrights Horizons, also starring Sigourney Weaver. Nielsen portrayed Bootsie Carp in the 2007–08 production of Charles Busch's Die, Mommie, Die! at New World Stages. She has also appeared at the Guthrie Theater and in many regional theatre productions.
Film
Nielsen's first film appearance was in the 1999 filmAdvice from a Caterpillar. She next played the role of Emily Bailey in the Woody Allen film Small Time Crooks. She has since appeared in the 2007 filmThe Savages starring Laura Linney, 2010's Morning Glory starring Rachel McAdams, and That's What She Said.
Television
Nielsen's first television appearance was on a 1990 episode of Tales from the Crypt. She has also appeared on Third Watch, Conviction, two episodes of Law and Order, and three episodes of Political Animals as Alice, starring Sigourney Weaver.
