Holby City is a British medical drama television series that aired weekly on BBC One. It was created by Tony McHale and Mal Young as a spin-off from the established BBC medical drama Casualty, and premiered on 12 January 1999; the show ran until 29 March 2022. It follows the lives of medical and ancillary staff at the fictional Holby City Hospital, the same hospital as Casualty, in the fictional city of Holby, and features occasional crossovers of characters and plots with both Casualty and the show's 2007 police procedural spin-off HolbyBlue. It began with eleven main characters in its first series, all of whom subsequently left the show. New main characters were then periodically written in and out, with a core of around fifteen main actors employed at any given time. In casting the first series, Young sought actors who were already well known in the television industry, something which has continued throughout its history, with cast members including Patsy Kensit, Jane Asher, Robert Powell, Ade Edmondson and John Michie.