This article contains a list of jargon used to varying degrees by railfans, trainspotters, and railway employees in the United Kingdom, including nicknames for various locomotives and multiple units. Although not exhaustive, many of the entries in this list appear from time to time in specialist, rail-related publications. There may be significant regional variation in usage.

A railfan, rail buff or train buff, railway enthusiast, railway buff or trainspotter, is a person who is recreationally interested in trains and rail transport systems.