<P> 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 . </P>
<P> 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 . </P>
who plays brenda 's mom on six feet under
who plays brenda 's mom on six feet under
Joanna Cassidy
Joanna Cassidy