Justin Kirk (born May 28, 1969^[1]) is an American actor. He gained prominence for his roles as Prior Walter in the HBO miniseries Angels in America (2003), for which he received a nomination for the Primetime Emmy Award for Outstanding Supporting Actor in a Miniseries or a Movie, and Andy Botwin in the Showtime dark comedy series Weeds (2005–2012).

Kirk was born in Salem, Oregon.^[1] His mother was of Russian-Jewish descent and his father was of Danish and English ancestry.^[2]

Kirk grew up in Union, Washington,^[1] where he attended a grade school on a Native American reservation, until his family moved to Minneapolis, Minnesota, when he was 12 years old. He attended high school there and performed at Children's Theatre Company.^[3][4]

Kirk moved to New York City after graduating. He played guitar in several New York bands in the early 1990s, most notably The Dimestore Darlings.^[5] He completed a two-year conservatory acting program at Circle in the Square Theatre School.^[2][6]

Kirk began his career on stage appearing off-Broadway in productions such as The Applicant, Shardston, Loose Ends, Thanksgiving, and Lovequest Live.^[7] He made his Broadway debut in Frank Gilroy's play Any Given Day which was performed at the Longacre Theatre. From 1994 to 1995, he played Bobby Brahms in Terrence McNally’s award-winning play Love! Valour! Compassion! on and off-Broadway for which he received an Obie Award for Best Performance. He next starred as Stephen Hoffman in Jon Marans’s two-character play Old Wicked Songs, staged at the New York's Promenade Theatre and Los Angeles' Geffen Playhouse. In 2012, he appeared in the role of Trip Wyeth succeeding Thomas Sadoski in Jon Robin Baitz’s play Other Desert Cities.

Kirk made his television debut in the short-lived CBS drama series New York News. From 1999 to 2001, he starred in The WB comedy drama series Jack & Jill. In 2003, he played Prior Walter in the HBO miniseries Angels in America, directed by Mike Nichols and based on Tony Kushner's award-winning play of the same name. For his role, he received critical acclaim, earning a nomination for the Primetime Emmy Award for Outstanding Supporting Actor in a Miniseries or a Movie. He gained further acclaim and recognition for his starring role as Andy Botwin in the Showtime dark comedy series Weeds. The series ran for eight seasons.

In 2012, he was cast as the lead in the NBC sitcom Animal Practice. The series was canceled after nine episodes, due to low ratings.^[8] In 2015, he appeared in two episodes of WGN period drama series Manhattan and FX/FXX comedy drama series You're the Worst. In 2018, he joined the cast of Showtime comedy drama series Kidding, which was executive produced by Michel Gondry. In 2020, he began playing the role of Hamilton Burger in the HBO period drama series Perry Mason, based on the character of the same name by Erle Stanley Gardner. In 2021, he appeared in the HBO drama series Succession as Congressman Jeryd Mencken.

Kirk first appearance on screen was in the Mike Nichols' 1994 romantic horror film Wolf in a photograph as Laura Alden's deceased brother. He credited Ann Roth, Nichols' longtime costume designer with whom he previously worked on the play Any Given Day for the job.^[9] He made his feature film debut in the 1997 drama film Love! Valour! Compassion! recreating his stage role. His other film credits include Vamps (2012), Mr. Morgan's Last Love (2013), Justice League: War (2014), Ghostbusters (2016), Molly's Game (2017), The Tribes of Palos Verdes (2017), and Vice (2018).