is an American actress. She is best known for her roles as Lisa Miller on the sitcom NewsRadio (1995–1999), Abby Lockhart on the medical drama ER (1999–2009), and Helen Solloway on the mystery drama The Affair (2014–2019), the last of which won her a Golden Globe Award.
Tierney has also appeared in numerous films, including Primal Fear (1996), Liar Liar (1997), Primary Colors (1998), Forces of Nature (1999), Insomnia (2002), Baby Mama (2008), Beautiful Boy (2018), The Report (2019), and The Iron Claw (2023).