Casualty series 31

The thirty-first series of the British medical drama television series Casualty commenced airing on BBC One in the United Kingdom on 27 August 2016, and concluded on 29 July 2017. The series consisted of 44 episodes, including the show's feature-length thirtieth anniversary special episode, "Too Old for This Shift". Erika Hossington continued her role as series producer, while Oliver Kent continued his role as the show's executive producer until the end of the series. Seventeen cast members reprised their roles from the previous series with original character Lisa "Duffy" Duffin returning to the series as part of the show's thirtieth anniversary. Rik Makarem appeared in the series between October 2016 and January 2017 as first year foundation doctor (F1) Sebastian Grayling. This series also featured the death of regular character Caleb Knight (Richard Winsor), who has appeared since series 28.

The opening episode of the series was a special feature-length episode, celebrating thirty years of the medical drama. The episode featured main character crossovers from Holby City, with Jac Naylor (Rosie Marcel), Henrik Hanssen (Guy Henry) and Adrian "Fletch" Fletcher (Alex Walkinshaw) appearing in the episode. Various former characters who have appeared in previous series throughout the thirty years of broadcast also made guest appearances during the episode. The episode features both the main characters lives, and the hospital itself in danger when an air ambulance crashed in the emergency department car park. The episode was watched by 7.20 million viewers. A special soundtrack was recorded for the episode, by the BBC National Orchestra of Wales. The series concluded with a special episode, "One", filmed in a single-take, using one camera, forty microphones and five boom operators. Show co-creator Paul Unwin returned to the show to write the episode.

The series was well received by fans and critics alike. They enjoyed the opening episode and opined that the show deserved an award, but an air ambulance charity thought the episode was thoughtless. On 25 January 2017, Casualty was awarded Best Drama at the National Television Awards. On 11 April 2017, the show was nominated for Best Soap & Continuing Drama at the BAFTAs, but was unsuccessful. The helicopter crash won the award for Best Drama Storyline at the 2017 Inside Soap Awards; Charlie and Duffy's wedding and Cal's murder also received a nomination in the category.