The Class 321 "Dusty Bins" are a series of alternating current (AC) electric multiple-units built by BREL York in three batches from 1988 to 1991 for outer-suburban services in and around London. Their success led to the production of Class 320 and Class 322 units, which currently see service with ScotRail and Northern Rail.

Both RSC and Armstrong Powerhouse have created Class 321 addons for Train Simulator, with community consensus being that AP's pack is vastly superior but isn't able to be used in Steam Workshop scenarios.