Julianne Nicholson (born July 1, 1971) is an American actress. She is best known for her roles in the film August: Osage County (2013) and the television series Law & Order: Criminal Intent (2006–2009), Masters of Sex (2013–2014), Eyewitness (2016), and Mare of Easttown (2021), the lattermost of which earned her a Primetime Emmy Award.

Nicholson's other notable credits include Tully (2000), Ally McBeal (2001–2002), Kinsey (2004), Conviction (2006), Boardwalk Empire (2011–2013), Black Mass (2015), I, Tonya (2017), Togo (2019), The Outsider (2020), and Blonde (2022).

Early life
Nicholson was born and raised in Medford, Massachusetts (outside Boston), the daughter of Kate (née Gilday) and James O. Nicholson Jr. She is the eldest of four children.

After graduating from Arlington Catholic High School, she modeled in New York for six months, quit for a year, then resumed her modeling career in Paris for another six months. After returning to New York, she attended Hunter College as a general studies major for two years. While in New York, Nicholson supported herself by waitressing and eventually left school to study acting and begin her professional career.