The World at War is a 26-episode television documentary series on World War II, including the events leading up to it and following in its wake. The series was produced by Jeremy Isaacs for Thames Television (UK). Commissioned in 1969, it took four years to produce, such was the depth of its research. It premiered on ITV in 1973 at a cost of £4 million, a record (at the time) for a British television programme. The series was narrated by Laurence Olivier and its score was composed by Carl Davis.

It is often considered to be the definitive television history of the Second World War, and considered by some the finest example of the documentary form, although much critically important information, such as the systematic breaking of Germany's codes by Britain which allowed Germany's encrypted communications to be intercepted, remained classified at the time.