Nicolai Theodorius Nilssen Rygg (29 February 1872 – 27 September 1957) was a Norwegian economist and Governor of the Central Bank of Norway.

He was born in Stavanger as a son of shoemaker Ole Nilssen Rygg (1842–1908) and Ane Severine Larsdatter (1841–1913).

He was a deputy judge in Vesterålen District Court before studying economics in Göttingen and Genève in 1896 to 1897, later statistics in the United States from 1904 to 1905.

Rygg spearheaded the "par policy", in which the goal was to lead the  kr value back to pre-World War I level.

[1][3] He is also known for pressuring opposition leader Johan Ludwig Mowinckel to file a vote of no confidence against the socialist Hornsrud's Cabinet in February 1928.