The thirty-fifth series of the British medical drama television series Casualty began airing on BBC One in the United Kingdom on 2 January 2021. The series consists of 30 episodes, which focus on the professional and personal lives of medical and ancillary staff at the emergency department (ED) of the fictional Holby City Hospital. Loretta Preece continues her role as series producer. Sixteen regular cast members reprised their roles from the previous series and actor Michael Stevenson returned to the serial in episode fourteen as Iain Dean, a paramedic.