Kristen Angela Johnston was born on September 20, 1967, in Washington, D.C., and grew up in a suburb of Milwaukee, Wisconsin. She is the daughter of Rod Johnston, a former Republican state senator, and she has English and German ancestry.

She attended Whitefish Bay High School, graduating in 1985, after which she pursued a Bachelor of Fine Arts in Drama at New York University. During her formative years, she also spent some time as an exchange student in Sweden and South America, experiences that broadened her cultural perspective.

She trained further at the Atlantic Theater Company Acting School in New York City, developing her craft on stage.

Her acting career began with theater roles, where she earned critical acclaim and was nominated for Drama Desk awards. Her breakthrough came with the role of Sally Solomon, the alien disguised as a woman in the NBC sitcom "3rd Rock from the Sun" (1996-2001).

This role won her two Primetime Emmy Awards for Outstanding Supporting Actress in a Comedy Series in 1997 and 1999, and she garnered several nominations including a Golden Globe and Screen Actors Guild nominations for the same role.

She became well-known for her comedic timing, physicality, and distinctive deep voice. On television, she further appeared in series such as "The Exes," playing divorce attorney Holly Franklin, and "Mom," where she portrayed the recovering addict Tammy Diffendorf. She also had guest roles in shows like "Sex and the City," earning recognition for memorable performances.

In film, Kristen Johnston notably played Ivana Humpalot in "Austin Powers: The Spy Who Shagged Me" (1999), Wilma Flintstone in "The Flintstones in Viva Rock Vegas" (2000), as well as supporting roles in "Music and Lyrics" (2007), "Bride Wars" (2009), and "Vamps" (2012).

Her role choices often highlighted her comedic strengths and ability to engage audiences with quirky, strong characters. She has also been involved in stage productions including "The Women" and Shakespeare in Central Park performances.

Kristen Johnston has earned critical acclaim throughout her career, with her two Emmy wins standing out as major highlights. She has been nominated for numerous awards including the Golden Globes, Screen Actors Guild Awards, and American Comedy Awards. Beyond acting, Johnston is an author; her memoir "Guts: The Endless Follies and Tiny Triumphs of a Giant Disaster" (2012) became a New York Times bestseller, where she candidly shares her struggles with addiction and recovery.