Katherine first appeared in the season four premiere. She moved to the neighborhood after leaving it before. Katherine lived in Wisteria Lane twelve years ago, and she left for unexpected reasons. She used to live in Mike's former house, the Simms's place, with her first husband and their daughter Dylan. She was friends with Susan Mayer and Mary Alice Young. When the housewives are watching the new family move in, Susan recognizes Katherine and runs to her, in order to hug her. At her house, Katherine gets to know Susan's friends and immediately starts a small feud with Bree. She also introduces her new husband, Adam, who is a gynecologist, and her 17-year old daughter. Susan mentions that Dylan and Julie used to be best friends, but Dylan doesn't seem to remember Susan's daughter. Katherine throws herself a welcoming barbecue party, for all the neighborhood to appear. At the same party, Lynette reveals to have cancer and Edie makes her first appearance in public since her suicide attempt. Edie actually thinks the party was thrown in her honor. At the party, Julie talks to Dylan, and she tells her that she doesn't seem to remember most things that happened to her when living in the street twelve years ago, and that she has a recurring dream in which a man tries to grab her. Later in the episode, Adam finds his wife in a room, and asks her if "this is the room", to which she responds yes. She tells him that Dylan wants to stay in that room, but she won't allow it. In the next episode, Bree tries to steal a recipe from Katherine and overhears a conversation between the Mayfairs, in which Dylan tries to know more about her father. She is insistent, so Katherine slaps her and she runs upstairs. Adam then tells his wife that Dylan will keep asking questions, and Katherine tells him that they'll have to come up with better lies. Bree then tells this to her friends, and they all become suspicious of their new neighbor. At Susan's charades party, Katherine confesses that Dylan's father did the most horrible thing a father could do to a daughter. Coming back to her house from the party, she finds Dylan and Julie trying to break in into the locked room Dylan used to sleep in, she tells her daughter not to see Julie anymore. Later, Kaherine is in the room and tells Adam that her aunt Lillian, who is sick, is ready to come and stay in that room. She then lifts up a rug to reveal a gash on the floor and breaks down and cries. When her aunt comes to her house to die, Katherine discovers that she wants to tell Dylan the truth. Katherine doesn't want her daughter to know what happened, so she steals the ringing bell from her aunt, who then writes a small note and dies, dropping the piece of paper containing the truth under the bed. Katherine later runs for president of the Homeowners' Association, opposite Lynette. When Dylan tries to learn more about her father, Katherine makes up a story to stop her. Adam is later visited by Sylvia Greene, a woman who was his patient back in Chicago, and who is in love with him. In episode 4.09, Katherine learns that Sylvia visited Adam. Greene later locks herself in Bree's bathroom, after Bree tried to find out the reason to why Katherine and Sylvia had a disagreement in the middle of the street, and Sylvia says she won't come out unless Adam goes get her. Bree calls Katherine, and Adam comes along, but she won't come out, forcing the three of them, along with Orson and baby Benjamin, to hide in a closet room. Hidden in the closet, Katherine discovers that Adam had sex with Sylvia, and that she's not just an erotomaniac. After the tornado, Katherine kicks Adam out of their house, but he discovers the note and gives it to her. Katherine rips it and throws it in the fireplace. The morning after, Dylan puts the burnt pieces together, reads the note, and discovers the truth.
- Delany had originally been offered the role of Bree Van de Kamp (later Hodge) prior to the series debut.
- Delany is the third actress in the series who portrayed Lois Lane. The first one is Teri Hatcher and the second is Lesley Ann Warren, who played Susan Mayer's mother, Sophie.
|Current Main Supporting Characters||
Carlos Solis · Tom Scavo · Orson Hodge · Angie Bolen · Ana Solis · Mike Delfino · Julie Mayer · Karen McCluskey · Nick Bolen · Danny Bolen · Porter Scavo · Parker Scavo · Penny Scavo · Juanita Solis · M.J. Delfino · Celia Solis · Lee McDermott · Bob Hunter · Karl Mayer · Andrew Van de Kamp · Preston Scavo
|Former Supporting Main Characters||
Rex Van de Kamp · John Rowland · Dave Williams · George Williams · Jackson Braddock · Matthew Applewhite · Caleb Applewhite · Betty Applewhite · Paul Young · Zach Young · Austin McCann · Kayla Scavo · Dylan Mayfair · Danielle Katz
Adam Mayfair · Victor Lang · Ida Greenberg · Stella Wingfield · Ian Hainsworth · Nora Huntington · Alma Hodge · Alex Cominis · Phyllis Van de Kamp · Gloria Hodge · Xiao-Mei · Martha Huber · Felicia Tilman · Bradley Scott · Maria Scott · Ed Ferrara · Roy Bender · Justin · Millicent Tilman