Maggie Siff (born June 21, 1974) is an American actress. She is best known for her television roles as department store heiress Rachel Menken Katz on the AMC drama Mad Men, Tara Knowles on the FX drama Sons of Anarchy, and psychiatrist Wendy Rhoades on the Showtime series Billions. She has had roles in the films Push (2009) as Teresa Stowe and Leaves of Grass (2010) as Rabbi Renannah Zimmerman. She stars in an indie film called A Woman, a Part (2016) as well as a minor role in a drama film called One Percent More Humid (2017).
Siff was born in The Bronx, New York City. Her father is Jewish (from a family from Russia), and her mother is of Irish and Swedish descent; she has said that she feels "culturally Jewish". She is an alumna of The Bronx High School of Science and of Bryn Mawr College, where she majored in English and graduated in 1996. She later completed an M.F.A. in acting at New York University's Tisch School of the Arts Graduate Acting Program.