NSB Class 66 (Norwegian: NSB type 66) was a three-car electric train used by the Norwegian State Railways for express trains on the Østfold Line to Halden and Gothenburg, and the Sørlandet Line to Kristiansand and Stavanger.

The four multiple units were built by Skabo Jernbanevognfabrikk, with motors from Norsk Elektrisk & Brown Boveri, and delivered in 1945–46.

With a power output of 474 kW (636 hp), it was the first train capable of 120 kilometers per hour (75 mph) in Norway.

Four Class 66 units were ordered by the Norwegian State Railways (NSB) in 1939, to be used as express trains on the then newly or shortly-to-be electrified Sørland- and Østfold Lines.

At the same time, similar Class 88 diesel multiple units were ordered for the non-electrified Bergen- and Dovre Lines.

The trains were built by Strømmens Værksted, Skabo Jernbanevognfabrikk and Norsk Elektrisk & Brown Boveri (NEBB).

[1] During construction, which occurred during World War II, there were several modifications, delays and accidents during construction to avoid the trains being finished before the war ended; this was to avoid the finished trains to be able to assist the German occupation forces.

It reduced travel time to Halden to 1 hour and 53 minutes, and was branded as the Østfold Express.

The high speed prohibited standing, and all passengers were required to purchase a seat reservation for 4 kr.

[1] On 15 November 1950, one unit was involved in the Hjuksebø train disaster, and the end car needed to be fully rebuilt.

However, the Stavanger Express did not prove a success, featuring low passenger numbers, and the last train ran on 24 August 1958.

[1] During the 1960s, the new El 13 locomotives were delivered, and locomotive-hauled express trains replaced the multiple units.