Parker Christian Posey (born November 8, 1968) is an American actress. She was known for her roles in independent films in the 1990s, such as Dazed and Confused (1993), Party Girl, The Doom Generation, Kicking and Screaming (all 1995), The Daytrippers (1996), The House of Yes, Clockwatchers (both 1997), and Henry Fool (1998). She has received nominations for a Primetime Emmy Award and a Golden Globe Award.
Although she began to work in bigger projects during the late 1990s, Posey has continued to work in small-scale features such as Personal Velocity: Three Portraits (2002), Fay Grim (2006), Broken English (2007), and Columbus (2017). Her more mainstream credits include You've Got Mail (1998), Scream 3 (2000), Josie and the Pussycats (2001), The Sweetest Thing (2002), Blade: Trinity (2004), Superman Returns (2006), Café Society (2016), and Beau Is Afraid (2023). She frequently works with Christopher Guest and has co-starred in several of his mockumentaries: Waiting for Guffman (1996), Best in Show (2000), A Mighty Wind (2003), For Your Consideration (2006), and Mascots (2016).
On television, Posey appeared in the recurring role on BYUtv's Granite Flats (2015), co-starred on all three seasons of Netflix's Lost in Space (2018–2021), and earned praise for the HBO Max miniseries The Staircase (2022). She has since starred in the third season of the HBO anthology series The White Lotus (2025).