Kathryn Joosten was born Kathryn Rausch in Chicago, Illinois to Dutch-German parents. Her first career was as a psychiatric nurse at Michael Reese Hospital in Chicago, living in nearby Lake Forest, Illinois, where she married a psychiatrist and raised two sons. Following her 1980 divorce, she began acting in community theater in 1982, at age 42. In 1992, she was hired as a street performer working for Disney World in Orlando, Florida. In 1995, she moved to Hollywood, where she took guest roles in television series such as Roseanne, Home Improvement, Picket Fences, Murphy Brown, ER, Seinfeld, Frasier, Just Shoot Me!, Buffy the Vampire Slayer, Dharma & Greg, Las Vegas and The Drew Carey Show. In a 1997 episode of Frasier, “Roz’s Turn”, Joosten appeared as Vera, the mother and personal secretary of Frasier’s conniving agent, Bebe Glazer, played by Harriet Sansom Harris. The pair would later be reunited to play opposite neighbors in Desperate Housewives. In 1999, Kathryn Joosten took the role of Mrs. Landingham, personal secretary to President Josiah Bartlet (played by Martin Sheen) in The West Wing. Joosten played the role for two seasons, until her character’s death in a car crash in 2001, and returned to the show twice more in flashback appearances. Her role on The West Wing gave her an entrance into more significant guest roles on notable television series. Since 2001, she appeared in such shows as Scrubs (appearing in “My Old Lady”, which won a Humanitas Prize as well as reappearing in two later episodes), My Name is Earl, Spin City, The X-Files, Judging Amy, Monk, Charmed, Will & Grace, Malcolm in the Middle, Grey’s Anatomy, The Suite Life of Zack & Cody, Reba, So Little Time, Gilmore Girls, The Closer and a recurring role as one of the less intimidating incarnations of God seen by the title character (played by Amber Tamblyn) on the TV series Joan of Arcadia. In 2005, Joosten appeared in the film Wedding Crashers, starring Vince Vaughn and Owen Wilson.

Joosten had a recurring role on Desperate Housewives as Karen McCluskey. For this role, Joosten won two Emmy Awards for Outstanding Guest Actress in a Comedy Series in 2005 and 2008 and once again was nominated for 2010, and appeared as a presenter at the 2005 and 2008 Emmy Awards telecasts. She received Screen Actors Guild Award nominations with the rest of the cast for Outstanding Performance by an Ensemble in a Comedy Series from 2006–2008. She was promoted to a member of the regular cast in Season 6. However, the Emmys still billed her as a “Guest Actress” when she was nominated for a third time for Outstanding Guest Actress in a Comedy Series for the 2010 Emmys. She was then nominated for a fourth Emmy, this time for Primetime Emmy Award for Outstanding Supporting Actress in a Comedy Series in 2012. She played Aunt Jackie in Alvin and the Chipmunks: The Squeakquel in 2009. In 2009, Kathryn Joosten and Lily Tomlin were in talks to star in a Desperate Housewives spin-off. The spin-off was given a preliminary green light to proceed. However, the series did not proceed. Kathryn Joosten died of lung cancer on the morning of June 2, 2012, after an 11-year battle with the disease. Coincidentally, her death occurred twenty days after the onscreen death from cancer of her Desperate Housewives character, Karen McCluskey. Poignantly, viewers in the United Kingdom first saw her onscreen death the day after her real life passing.