Most of us will know O'Mara for playing the renegade Timelord, The Rani, in The Mark of the Rani and Time and the Rani, but she was also known for playing Cassandra 'Caress' Morrell in US soap Dynasty and roles in such shows as Howard's Way, Triangle, Bad Girls and Absolutely Fabulous. Her career spanned six decades, until her final role as Mrs Simmonds in a 2012 episode of Benidorm.
Her agent, Phil Belfield, said:
"She was extraordinary, she had so much energy and vitality with a love for theatre and acting.
A shining star has gone out, and Kate will be dearly missed by all who knew and have worked with her."
Former Doctor Who co-stars have also tweeted about the loss, with Colin Baker tweeting:
"Oh my goodness. Kate O'Mara is no longer with us. Sad sad news. A delightful, committed and talented lady and actress. We are the poorer."And Bonnie Langford tweeting:
"So sad to hear that the wonderful Kate O'Mara has gone. Treasured memories."Our thoughts are with Kate's family and friends at the difficult time.