Best known for playing Alexis Colby’s scheming sister Cassandra “Caress” Morrell in the US soap in the mid 1980s, she also starred in British series Doctor Who, Howards’ Way, and Triangle.
Her agent Phil Belfield said she died yesterday morning in a nursing home in Sussex after a short illness.
“She was extraordinary, she had so much energy and vitality with a love for theatre and acting,” he said. “A shining star has gone out and Kate will be dearly missed by all who knew and have worked with her.”
O’Mara’s first television roles were in the 1960s. But it was in the 1980s that she landed her biggest and longest-running roles.
As well as Dynasty, she played a ruthless businesswoman in BBC drama Howards’ Way.
She also appeared in the original run of Doctor Who as renegade Time Lord The Rani.
In the 1990s she starred as Jackie in the comedy show Absolutely Fabulous, the sister of Patsy, who was played by Joanna Lumley.
More recently she had appeared in ITV soap Benidorm and in a 2012 stage adaptation of Agatha Christie’s Death On The Nile.
She is survived by her sister, the actress Belinda Carroll.