The SR Z class was an 0-8-0T 3-cylinder tank engine designed by Richard Maunsell and intended for heavy shunting on the Southern Railway, the first eight entering into service in 1929. It was a successful design and would have been built in greater numbers, but an order for a further ten was cancelled in 1930 due to the reduction in freight traffic as a result of the Great Depression.

Under the Whyte notation for the classification of steam locomotives, 0-8-0 represents the wheel arrangement of no leading wheels, eight powered and coupled driving wheels on four axles and no trailing wheels. Locomotives of this type are also referred to as eight coupled.