The World at War is a 26-episode British documentary television series that chronicles the events of the Second World War. It was produced in 1973, at a cost of £900,000 (equivalent to £11,600,000 in 2021), the most expensive factual series ever produced. It was produced by Jeremy Isaacs, narrated by Laurence Olivier and included music composed by Carl Davis. The book, The World at War, published the same year, was written by Mark Arnold-Forster to accompany the TV series.

The World at War attracted widespread acclaim and now it is regarded as a landmark in British television history. The series focused on a portrayal of the experience of the conflict: of how life and death throughout the war years affected soldiers, sailors and airmen, civilians, concentration camp inmates and other victims of the war.