Stephanie Janette Block (born September 19, 1972) is an American actress and singer, known for her work in Broadway musicals. A three-time Tony Award nominee, she was nominated for Best Actress in a Musical for The Mystery of Edwin Drood in 2013, for Best Featured Actress in a Musical for Falsettos in 2017, and finally winning as Best Actress in a Musical for The Cher Show in 2019. She is also a six-time Drama Desk Award nominee (and one-time winner) and has appeared on numerous cast recordings. In 2009, she released a solo album, This Place I Know.

Block began her professional musical career in regional theater and by playing Belle in the Disneyland production of Beauty and the Beast in 1992. She made her Broadway debut in the 2003 original production of The Boy from Oz, playing Liza Minnelli. Having read the part of Elphaba in the first reading of Wicked in 2000, she was the first actress to play the role in the US touring production from 2005–06, winning the Helen Hayes Award for Best Actress in a Non-Resident production. She later reprised the role on Broadway from 2007–08. She received Drama Desk nominations for the Off-Broadway productions of By the Way, Meet Vera Stark (2011) and Little Miss Sunshine (2013), and for the Broadway productions of 9 to 5 (2009), The Mystery of Edwin Drood (2012), Falsettos (2016) and The Cher Show (2019).