Caledonian Sleeper is the collective name for overnight sleeper train services between London and Scotland, in the United Kingdom. It is one of only two currently operating sleeper services on the railway in the United Kingdom, the other being the Night Riviera which runs between London and Penzance.

Two services depart London Euston each night from Sunday to Friday and travel via the West Coast Main Line to Scotland. The earlier departure divides at Edinburgh into portions for Aberdeen, Fort William and Inverness. The later departure serves Edinburgh and Glasgow splitting at Carstairs. Five London-bound portions depart from these destinations each night, combining into two trains at Edinburgh and Carstairs.

Since April 2015, the Caledonian Sleeper has been a standalone franchise operated by Serco, and under the supervision of the Scottish Government. Prior to this, it was part of the ScotRail franchise. In 2019 a new fleet of Mark 5 carriages replaced the existing carriages.