Doctor Who Star Kate O'Mara Dead at 74 Actress also starred in 'Dynasty,' 'Absolutely Fabulous' By Newser Editors and Wire Services Posted Mar 30, 2014 9:07 AM CDT 2 comments Comments In Oct. 6 1998 file photo, British actress Kate O'Mara, who has died at the age of 74. (AP Photo/PA, Michael Walter, File) (Newser) – Actress Kate O'Mara, who starred in the 1980s soap opera Dynasty as well as the original Doctor Who series, has died at the age of 74. Her agent Phil Belfield said O'Mara died today in a nursing home in southern England after a short illness. The actress, who began her television career in the 1960s, became a household name for playing Alexis Colby's scheming sister Cassandra "Caress" Morrell in Dynasty. She also appeared in the BBC drama Howards' Way, as well as the 1990s comedy Absolutely Fabulous with Joanna Lumley.