Konrad Hartvig Isak Rosenvinge Nielsen (28 August 1875 – 27 November 1953) was a Norwegian philologist.

He was born in Vik i Helgeland as a son of politician Sivert Andreas Nielsen (1823–1904) and his wife Jonette Cornelie Falch Heide (1833–1925).

In 1897 and 1898 he took exams in Kven and Sami languages, and from 1898 to 1899 he studied Finnish at the University of Helsinki.

[1] In July 1899 Nielsen was appointed as a lecturer in Kven and Sami at the Royal Frederick University.

degree at the University of Helsinki with the thesis Die Quantitätsverhältnisse im Polmak-lappischen, about the language in Polmak.