List of companies operating trains in the United Kingdom

There are several companies operating trains in the United Kingdom. These include the operators of passenger services, which are, rather confusingly, officially referred to as "train operating companies" or TOCs, as distinct from "freight operating companies".
Passenger operators in Great Britain.
Current passenger operators.
The following operate the services that comprise the National Rail network in Great Britain.
There are also several heritage lines and light rail systems.
Defunct operating companies.
A number of operating companies have ceased to exist for a number of reasons, including premature withdrawal of the franchise; the natural term of the franchise has expired; bankruptcy; or there has been a merger.
Passenger operators in Northern Ireland.
In Northern Ireland passenger trains are still government-owned, under the auspices of Translink. The following brands are used:
Railtour operators.
In Northern Ireland