The thirty-third series of the British medical drama television series Casualty began airing on BBC One in the United Kingdom on 11 August 2018, one week after the end of the previous series. The series consisted of 46 episodes. Lucy Raffety continues her role as series producer, while Simon Harper continues his role as the show's executive producer. Sixteen regular cast members reprised their roles from the previous series. The series, which is billed as "The Year of the Paramedic", begins with a motorway collision stunt sequence, and features a crossover episode with spin-off series, Holby City. This series featured the departures of six cast members, including Amanda Mealing as Connie Beauchamp, Azuka Oforka as Louise Tyler and Chelsea Halfpenny as Alicia Munroe. Four new regular cast members also joined the series, while two actors began appearing in a recurring capacity.

Casualty (stylised as CASUAL+Y) is a British medical drama series that airs weekly on BBC One. Created by Jeremy Brock and Paul Unwin, it was first broadcast in the United Kingdom on BBC One on 6 September 1986. The original producer was Geraint Morris. Having been broadcast weekly since 1986, Casualty is the longest-running primetime medical drama series in the world.