City Night Line (abbreviated CNL, white & red livery) is a category of Deutsche Bahn overnight passenger train service in Europe. The lines were originally operated by the former railway company CityNightLine AG. Like DB AutoZug GmbH, the company was a wholly owned subsidiary of Deutsche Bahn and was integrated in the DB Group as from 1 January 2010 in the form of an asset deal.
In 1998, Deutsche Bahn hived off its night train services, which were provided with the train categories EN (EuroNight) and UEx (Urlaubsexpress), from DB Fernverkehr AG to DB AutoZug GmbH. One year later, the CityNightLine AG company, domiciled in Zurich and until then a joint venture operated by Deutsche Bahn and the state-owned railways of Austria and Switzerland, ÖBB and SBB, became a wholly owned subsidiary of DB Fernverkehr AG. It was run by the same management team as DB Autozug GmbH, so that responsibility for all night train categories, which still form the core element of the City Night Line network, lay with one single source from then on. The management of services, rolling stock and pricing of CityNightLine and its then DB counterpart (NachtZug), however, remained separate.