Joosten passed away at home in Westlake Village, California, it has been reported. She had previously suffered from lung cancer, but at present her cause of death is unknown.
The actress portrayed Karen McCluskey on the hit ABC series, and appeared in all eight seasons of the show. She received Emmys in 2005 and 2008 for 'Outstanding Guest Actress in a Comedy' for her role as Wisteria Lane's curtain-twitching neighbour, with Joosten claiming that people found the character "relatable to every family".
Felicity Huffman, who starred alongside Joosten as Lynette Scavo, also wrote a sweet tribute on Twitter: ""All my prayers and love to Katherine Joosten's family. Rest in peace, she was an amazing woman and a wonderful actress."
Joosten was also famous for her role on The West Wing as Delores Landingham, secretary to Martin Sheen's President Josiah Bartlett.
A latecomer to show business, Joosten did not begin taking acting classes until the age of 42, after previously working as a psychiatric nurse. Since then her TV career saw her take roles in Roseanne, Home Improvement, ER, Seinfeld, Frasier, Just Shoot Me!, Scrubs and Buffy the Vapire Slayer.
Such sad news, especially after the last episode of Desperate Housewives only aired a few weeks ago.