BBC's Miss Marple
In the BBC 1987 adaptation of the novel, Kevin Halliday is portrayed by Gary Watson. Only his voice is heard during a voiceover when Gwenda Reed is reading a diary he had left behind at the Saltmarsh House nursing home.
ITV's Agatha Christie's Marple
In the ITV 2006 adaptation of the novel, Kelvin Halliday is portrayed by Julian Wadham.
Here he is not a military officer but a civil servant at Government House in Delhi with the grade of Third Secretary. He has a much larger role and more screen time than in the other adaptations. There are a few flashbacks of him with his baby daughter Gwenda in Delhi and later in Dillmouth. There are also a few scenes of him with Helen Marsden including one of him proposing to her. In this adaptation, Halliday never married Helen. They were engaged to marry but she never turned up at the registry office. Some time after Helen's disappearance, Halliday was himself found dead at the foot of a cliff.
Halliday's death was at first thought to be suicide but it was revealed at the end of the episode that Dr Kennedy had pushed him over. Halliday has a grave in Dillmouth in this adaptation.
NHK's Anime adaptation
Halliday also has a lot of screen time in NHK's anime adaptation of Sleeping Murder. There are extended scenes dramatising courting Helen on board the ship from India, also scenes of him and Helen inviting the Erskines to Hillside for tea, as well as some scenes in the aftermath of Helen's disappearance. However, the voice actor behind the character is not credited.