A Star class locomotive was a particular type of steam locomotive of the Great Western Railway. In total, 73 were built, but some were later rebuilt as Castle Class locomotives. One, 4003 Lode Star, survives in preservation as a static, non-working, exhibit.

The prototype was an experimental locomotive, 4000 North Star (originally given number 40), constructed with the 4-4-2 wheel arrangement for comparative trials with 4-cylinder compound locomotives of the de Glehn type purchased from France. This established the benefits of the 4 cylinder layout, but with simple expansion, and a 4-6-0 wheel arrangement. As in the de Glehn design, the outer cylinders drove the centre driving axle, the inside pair of cylinders were set well forward and drove the leading driving axle. There were just two set of Walchaert 's valve gear between the frames, the valves to the outside cylinders being driven by rocking levers.

An enlarged version of the design was introduced in 1923, this was the Castle Class locomotive, of which about 170 were constructed, including the rebuilds from the Star class mentioned above.

List of Locomotives