who plays brenda's mom on six feet under
List of Six Feet Under characters Margaret Chenowith, played by Joanna Cassidy, is Brenda and Billy's dysfunctional mother and a psychologist. Her bouts of misplaced anger can be seen throughout the series. In the 1960s, she met her future husband, Bernard Chenowith in therapy when she was working as an intern. The couple married in 1967. In the 1970s, the Chenowiths had become controversial for allowing their daughter Brenda to undergo testing by the controversial Gareth Feinberg, who later wrote Charlotte: Light and Dark about Brenda. Though Margaret and Bernard have an open marriage, they separate briefly in 2002 after Bernard lies about an infidelity. The two later renew their vows and soon after, Bernard dies of cancer in early 2003. Margaret moves on and begins dating her son's former lover (and art teacher), Olivier Castro-Staal.