Kathryn Joosten: US actress who starred in Desperate Housewives

Brought humanity to a nosy, meddlesome character: Joosten with her Best Guest Actress Emmy in 2005 (Reuters)

The American actress Kathryn Joosten was known to millions of television viewers worldwide as Karen McCluskey, the nosy, gossipy neighbour in Desperate Housewives, observing the lives and relationships of the group of women in the fictional Wisteria Lane.

Usually referred to as Mrs McCluskey, rather than Karen, the character was meddlesome and trouble-making, but Joosten's portrayal made her three-dimensional, showing her deep down to have a heart of gold.

Mrs McCluskey also harboured skeletons in her cupboard that, in a popular television comedy-drama, were inevitably revealed during its run (2005-12). She once modelled underwear to pay her way through college; she had a son who died at the age of 12; and her dead husband was to be found in her basement freezer – because he had failed to update his pension plan, which would have left all his assets to his first wife.

Often seen babysitting the children of Lynette Scavo (Felicity Huffman), who battled cancer, Mrs McCluskey herself died of cancer in the final episode of Desperate Housewives – with her spirit joining those of other dead Wisteria Lane residents – screened in the US less than three weeks before the actress's own death from the disease.

"I joke about this being a practice session, but there is a cathartic aspect to it," said Joosten, who won Emmy Awards in 2005 and 2008 as Outstanding Guest Actress in a Comedy Series.

Karen McCluskey was the second character for which Joosten became known globally after turning professional as an actress in her 40s. In the first two series of The West Wing (1999-2001), she played President "Jed" Bartlet's personal secretary, Delores Landingham, who was not afraid to talk to her boss bluntly and abruptly, which was acceptable because of the maternal manner in which she did so – and because of the fact that she had done the same job for his father, a prep school headmaster. Joosten's run ended when Delores died in a car crash, although she was seen in flashback three times (2001-02).

Born in Florida in 1939, Joosten worked as a psychiatric nurse in a medium-security unit of Michael Reese Hospital, Chicago, and married a psychiatrist. After the couple divorced in 1980, Joosten blaming his alcoholism, she decided to pursue her childhood dream of acting and gained experience with the Steppenwolf Theatre Company in Chicago.

At the same time, the single mother earned money by painting and decorating her neighbours' houses in the Lake Forest suburb and as a Welcome Wagon company sales rep, delivering baskets of gifts supplied by local businesses to new homeowners.

She then worked in semi-professional theatre, made her screen debut in the film Grandview, USA (1984) and took bit parts in several television programmes.

In 1992, Joosten moved to Orlando, Florida, to work as a street performer at Disney World. Three years later, she headed for Hollywood and was quickly spotted by television casting directors.

Small roles followed in episodes of Picket Fences (1995), Chicago Hope (1995), 3rd Rock from the Sun (1996), Murphy Brown (1996), Seinfeld (1997), Frasier (1997, as the mother and secretary of the title character's conniving agent) and NYPD Blue (1997).

Although her first regular role, as Mrs Sturges in Thanks (1999), ended with the axing of that comedy about the trials and tribulations of a 17th-century Puritan family in Massachusetts, Joosten was then cast in The West Wing. She also had short runs in the chalk-and-cheese married-couple sitcom Dharma & Greg (2000-2001) and Scrubs (2001, as a hospital patient deciding to face death rather than prolong her life with dialysis).

In 2001, Joosten stopped smoking after being diagnosed with lung cancer and, after going into remission, was busier than ever. She enjoyed guest roles in programmes such as The X-Files (2002), Charmed (2003), Strong Medicine (2003), Will & Grace (2004), Grey's Anatomy (2005), Malcolm in the Middle (2005) and The Mentalist (2012), as well as almost 20 films, including Wedding Crashers (2005).

When her other lung was hit by the disease in 2009, she underwent surgery, subsequently campaigning for cancer and anti-smoking charities, and calling herself a "lung cancer survivor" but acknowledging that she would live with it for the rest of her life.

Joosten persuaded Desperate Housewives' creator, Marc Cherry, to write it into the programme's storyline to highlight public awareness. Her character's screen death will be seen in Britain next week.

Anthony Hayward

Kathryn Joosten, actress: born Eustis, Florida 20 December 1939; married (marriage dissolved 1980; two sons); died Westlake Village, California 2 June 2012.