The list is not complete, contributions and corrections are received with thanks! Please also take a look here!
Overview of updates here (Traintracks.eu) (in German). Also take a look here (Night-trains.com). And at this nice map (by one of our members). Heinrich Böll Foundation has made these map (May 2021)
The ÖBB network
Regular NightJet services which are:
Wien-Bregenz (domestic)
Villach-Feldkirch (domestic)
Graz-Feldkirch (domestic)
Wien/Graz/Villach-Zürich
Hamburg/Berlin-Basel-Zürich
Wien-Hamburg/Düsseldorf
Innsbruck-Hamburg/Düsseldorf
Wien-Rome/Milano (runs via Klagenfurt or via Salzburg)
Wien-Venedig
Wien-Livorno (seasonal)
and
The EuroNight partnerships in collaboration with Balkan/East European countries:
Prague – Wien/Budapast (EN Metropol) also a section Budapest-Warszawa
München – Zagreb/Rijeka (EN Lisinski)
Wien-Warschawa/Krakow/Kosice
>> Advices on how to reach NightJet line from the UK (via Cologne)
Swedish night trains
SJ-nighttrain (Malmö-Stockholm)
SJ-nighttrain (Göteborg-Stockholm-Duved and Luleå)
The Polar Circle Express / SJ Norrlandståg (Stockholm-Kiruna-Narvik/Luleå)
Snälltåget in Sweden, seasonal (Malmö-Stockholm-Storlien/Röjan)
Berlin Night Express, seasonal (Malmö-Berlin) – operated by Snälltåget
In Norway (NSB)
Bergensbanen (Oslo-Bergen),
Sørlandsbanen (Oslo-Stavanger),
Dovrebanen (Oslo-Trondheim) and
Nordlandsbanen (Trondheim-Bodø)
In Finland (VR)
Helsinki/Turku–Rovaniemi/Kemijärvi
Tampere-Kolari
Helsinki-Moscow
In Poland (PKP)
Warszawa-Kiev
Warszawa/Wroclaw-Krakow-Lviv
Sczecin-Przemysl
Gdynia/Warszawa/Szczecin-Zakopane (separate trains)
Gdynia-Bielsko-biala
Kolobrzeg-Krakov
Swinoujscie-Warszawa
French lines – INTERCITÉS DE NUIT (couchettes only)
Paris – Toulouse – La-Tour-de-Carol (daily)
Paris – Rodez (daily)
Paris – Briançon (daily)
Paris – Perpignan – Port-Bou (runs only on Fridays, Sundays and during vacations)
Italian lines (Treni Notte)
Rome – Palermo/Syracuse (Lonely Planet: Super Sleeper Train) ## NEWS##
Palermo-Pisa-Genova-Milano
Milano-Roma-Palermo/Siracusa (a VERY long run)
Trieste-Venezia-Roma
Lecce-Bologna-Torino/Milano
Torino-Salerno
Torino-Lecce
Milano-Lecce
Lecce-Roma (not daily)
Bolzano-Verona-Roma (not daily)
Russian services to Western Europe
Moscow-Paris
Moscow-Nice
Moscow-Berlin (Talgo)
Other Eastern European locations
Wien – Budapest – Braşov – Bucureşti Nord, is called “Dacia”, a Romanian train
Bucureşti – Curdici (at the Hungarian border) – Wien, “Ister”
Braşov – Budapest, “Corona”
Bucureşti – Chişinău
Cheb – Košice
Cheb – Hummené
Prague – Košice- Kiev
Prague – Warszawa
Prague – Budapest
Bratislava-Kiev (R 801)
Budapest-Kiev
Bucureşti-Kiev (once a week)
Beograd – Sofia
Beograd – Bar (Montenegro)
Sofia – Istanbul (Sirkeci)
Prague – Split
Prague – Bar
Domestic Romanian trains with sleepers/couchettes:
Bucureşti-Timişoara
Constanța-Bucureşti-Arad
Bucureşti-Oradea-Satu Mare
Bucureşti-Baia Mare/Bistrița/Cluj
Bucureşti-Sighetu Marmației
Bucureşti-Vatra Dornei
Bucureşti-Suceava
Bucureşti-Iaşi
Timişoara-Iaşi (2 daily overnight trains)
Great Britain
Caledonian Sleeper: London-Glasgow/Edinburgh and further north to Fort William/Inverness/Aberdeen
Night Riviera Sleeper: London-Penzance
Trenhotel (in Spain and Portugal)
Madrid – A Coruña – Pontevedra, Rias Gallegas”
Madrid – Ferrol, “Atlántico”
Barcelona – A Coruña / Vigo, “Galicia”
Madrid – Lisbon, “Lusitania”
Lisbon – Hendaye (border to France)
Private and seasonal operations – often with car transport
Thello, Paris-Venice
BTE AutoReiseZug Hamburg-Lörrach
UrlaubsExpress, Hamburg-München-Innsbruck-Verona or Hamburg-München-Salzburg-Villach
EE-Autozug from Düsseldorf (Germany) to Livorno/Verona (Italy)
Optima Express Autoreisezug, Villach (Austria) – Edirne (Turkey)
Astra Trans-Carpatic from Arad to Bucureşti Nord via Sighişoara and Braşov
Schnee Express, Hamburg – Bludenz/Schwarzach, also a variation from Holland under the brand “Ski Train”