The South Australian Railways B class was a class of 2-4-0T steam locomotives operated by the South Australian Railways.

In 1856, the South Australian Railways ordered two 2-4-0 tender locomotives from Robert Stephenson and Company, the first arriving in November 1856 and the second in March 1858. They entered service on the Gawler and Outer Harbor lines. In 1875, both were rebuilt as 2-4-0T tank engines. In 1887, number 7 was rebuilt by Islington Railway Workshops as a crane locomotive with number 4 following in 1893. Both were withdrawn and scrapped in the 1930s.^[1]