The television star was best known for roles on The West Wing, Scrubs and most recently Desperate Housewives, in which she made her final appearance earlier this spring.
Below are just some of the responses to the tragic news of Joosten's death from friends, colleagues and celebrities:
"So sorry to hear Kathryn Joosten passed away today. A Great actress. West Wing & Desperate Housewives she was terrific. RIP Kathy."
"Saddened about the passing of Kathryn Joosten #MrsLandingham #TheWestWing it was an honour to work with you and an even greater honour knowing you Kathryn. #RIP"
"To the memory of an extraordinary woman, actress and friend. Rest in Peace Kathryn Joosten.Wisteria Lane won't be the same without you. @EvaLongoria. @ReallyMarcia @FelicityHuffman"
Yvette Nicole Brown
"I am heartbroken by the loss of my friend. Desperate Housewives actress Kathryn Joosten dies (sic) at 72"
"Very sad to hear of @KathyJoosten's death. She was a salt-of-the earth nurse who became a brilliant actor. Her comic timing was nonpareil... Kathryn spoke openly and passionately about her fight with lung cancer. It is our loss that she is gone."
Shonda RhimesVery sad about the death of Kathryn Joosten. She was on GA [Grey's Anatomy] in Season 1. But she'll always be Mrs. Landingham on West Wing for me."
"So sad to read that actress Kathryn Joosten passed away. Mrs. Landingham from The West Wing is one of my all time favourite TV characters... She was an incredible talent. May she be remembered as such and rest in peace."
"All my prayers and love to Katherine Joosten's family. Rest in peace, she was an amazing woman and a wonderful actress."
"Goodbye Karthryn (sic); our beloved Mrs Landingham. You will never truly be gone, film is forever. Tell Leo I love him."