The Western Region of British Railways (later British Rail) (WR or BR(W)) was one of the six regions created on nationalisation in 1948 and which lasted until reorganisation in the 1980s. The WR consisted principally of ex-Great Western Railway lines.

The Great Western Railway (GWR) was established during the 19th century. Although run down by the Second World War, its management opposed its nationalisation into British Railways and there would be power struggles, particularly with the powerful London Midland Region.

The WR built a large number of steam locomotives to GWR designs, even after the advent of diesel shunters . The BR standard class 3 was also built for the Western region.

WR experimented with diesel hydraulic traction such as the British Rail Class 52 Westerns, British Rail Class 35 Hymeks based on West German designs but these were eventually replaced as being non-standard.

The WR also had some territory changes over its existence, acquiring some ex-LMS lines in South Wales and west of Birmingham.