Edge of Darkness is a British television drama serial produced by BBC Television in association with Lionheart Television International and originally broadcast in six 50 to 55-minute episodes in late 1985. A mixture of crime drama and political thriller, it revolves around the efforts of widowed policeman Ronald Craven (played by Bob Peck) to unravel the truth behind the murder of his daughter Emma (played by Joanne Whalley). Craven's investigations soon lead him into a murky world of government and corporate cover-ups and nuclear espionage, pitting him against dark forces that threaten the future of life on Earth.

Writer Troy Kennedy Martin was greatly influenced by the political climate of the time, dominated by the Thatcher government, and the aura of secrecy surrounding the nuclear industry – and by the implications of the Gaia hypothesis of environmentalist James Lovelock; these combined to his crafting a thriller that mingled real world concerns with mythic and mystical elements. Kennedy Martin's original ending was more fantastic than that eventually used in the finished serial: he had proposed that Craven would turn into a tree but this was vetoed by members of the cast and crew.

First broadcast on BBC2, Edge of Darkness was met with such widespread critical acclaim that within days it had earned a repeat on BBC1. Winner of several prestigious awards, it remains highly regarded, often cited as one of the best and most influential pieces of British television drama. The series' director, Martin Campbell, filmed a remake, released in January 2010, starring Mel Gibson and set in the United States.