The NZR RM class Vulcan railcars were operated by the New Zealand Government Railways (NZR) in the South Island of New Zealand. All New Zealand railcars are classified as RM (Rail Motor), and this class derived their nomenclature from the name of the manufacturer, the Vulcan Foundry of Britain.

The RM class was the classification used by the New Zealand Railways Department (NZR) and its successors gave to most railcars and railbuses that have operated on New Zealand's national rail network. "RM" stands for Rail Motor which was the common name at the turn of the 20th century for what became known in New Zealand as railcars. As many types of railcars are operated, class names have been given to each railcar type to differentiate them from others.