The R class was an express passenger steam locomotive that ran on Australia's Victorian Railways (VR) from 1951 to 1974. A long overdue replacement for the 1907-era A2 class4-6-0, their development and construction was repeatedly delayed due to financial constraints caused by the Great Depression and later the manpower and materials shortages of World War II and the immediate postwar period.
Orders eventually totalling 70 locomotives were placed with the North British Locomotive Company of Glasgow. Once initial teething problems were overcome, R class locomotives proved to be a success and their power and speed enabled faster timetabled services. However, they were almost immediately superseded by mainline diesel-electric and electric locomotives on the Victorian Railways from 1952 onwards. With successive orders of diesel-electric locomotives through the 1950s and 1960s gradually displacing them, all but seven of the class were withdrawn and cut up for scrap.
Four of the remaining locomotives were later restored to operating condition between 1984 and 1998. These have seen use ranging from hauling special heritage train services through to substituting for modern diesel-electric locomotives on regular intercity rail services run by V/Line and West Coast Railway. Another surviving example, number R 704, was originally displayed at the Festival of Britain in 1951 and is now on permanent display at the Newport Railway Museum in Newport, Victoria.