Katherine Irma Mayfair is a fictional character created by Marc Cherry for the ABC television series Desperate Housewives.

The character was portrayed by Dana Delany and first appeared in the series' fourth season premiere on September 30, 2007, as the focus of the yearly mystery.

Though initially a homemaker, Katherine started a catering business with neighbor Bree Van de Kamp (Marcia Cross), with whom she shares "a heated rivalry.

"[6] She has been married twice, to Wayne Davis (Gary Cole) and Adam Mayfair (Nathan Fillion), but both relationships ended in divorce.

When Cherry was developing Katherine, a character with "a lot of Alpha female qualities and some slyness and darkness," he offered Delany the role.

Following her multi-episode guest role on another ABC series, Castle, network executives offered Delany the lead in a new pilot for the 2010-2011 television season.

[16] Delany filmed the pilot for Body of Proof in April 2010; her absence in Desperate Housewives was explained by having Katherine and her girlfriend, Robin Gallagher (Julie Benz), leave town indefinitely.

[16] In May, ABC picked up Body of Proof for thirteen episodes; thus, Delany did not return for the seventh season of Desperate Housewives as a series regular.

[9] When Katherine was introduced to the series, many critics noted that she was very similar to Bree Hodge (Marcia Cross), in that both prided themselves on their domestic skills.

"[22] Her cold exterior is noted by many characters, including Gabrielle Solis (Eva Longoria Parker), who remarks that Katherine is "smug and 'holier than thou'" and is "getting a reputation around [the neighbourhood] for having a stick up [her] ass!

"[23] Though Katherine immediately conflicts with the other women on the street,[14] most notably Bree,[21] she eventually develops close friendships with her neighbours.

[24] In the sixth season, however, Katherine "[morphs] into the person the housewives have to hate" in the absence of Edie Britt (Nicollette Sheridan).

[25] Later, in the fifth season, Katherine contemplates leaving Fairview because she is single, later revisiting the option in an attempt to force Mike to realize he loves her.

[15] When she becomes romantically involved with a woman, she puts her life in Fairview on hold indefinitely while trying to evaluate everything during an extended vacation in Paris.

Wayne became increasingly violent, forcing Katherine to flee with Dylan, and seek refuge with her aunt, Lillian Simms (Ellen Geer).

One year later, Katherine returned from a walk with Lilian and she found out that Wayne had visited Dylan while Mary Alice babysat her and gave her a new doll.

Fearing Wayne’s wrath, Katherine and Lillian buried Dylan in nearby woods and she left Wisteria Lane, lying Susan and Mary Alice that she had taken a job offer in Chicago.

Katherine's mysterious and cold exterior and Dylan’s lack of memories about life on Wisteria Lane raise the suspicions of their neighbors.

Sylvia Greene (Melora Walters), the woman who accused Adam of sexual harassment in Chicago, visits him, hoping to rekindle their romance.

Bree, Susan, Lynette, and Gabrielle tell the police that her actions were in self-defense and Katherine is finally integrated into their social group.

Katherine briefly moves in with Bree, a recovering alcoholic who relapses when her husband, Orson Hodge (Kyle MacLachlan), leaves for jail.

The couple elope to Las Vegas, but Mike leaves Katherine at the airport when he learns that their neighbor, Dave Williams (Neal McDonough), plans to kill M.J. in revenge for the deaths of his wife Lila and daughter Paige in a car accident.

When Mike hears that Katherine has told M.J. that Susan is a bad mother, he coldly tells her off and warns her to stay away from M.J. or else incur his wrath.

Susan worries that Katherine has suffered a nervous breakdown and asks Dylan to visit and have her mother committed for psychiatric observation.

Several months later, when Katherine returns to Wisteria Lane, she develops a friendship with Robin Gallagher (Julie Benz), a former stripper who moves in with Susan and Mike.

[33] Tim Stack of Entertainment Weekly confessed that while he is not a fan of Delany's acting, she is "perfect for this role and looks to be a choice adversary for Bree.

Matt Roush of TV Guide complimented the addition of Katherine, writing "while she's obviously harboring a dark secret, at least there's no one trapped in the basement," referencing the Betty Applewhite (Alfre Woodard) storyline from the second season.

[34] Following the 2007-2008 television season, Delany was a promising contender for an Emmy Award in the Outstanding Supporting Actress in a Comedy Series category,[33][35][36] though she did not receive a nomination.