Niels Aage Anton Nielsen^{[lower-alpha 1]} (born in Vejle 25 June 1913, died 16 January 1986) was a Danish professor of Nordic languages at Aarhus University.^[1] He was also a leader in the Danish resistance movement.^[2]

Nielsen was the son of master carpenter Niels Nielsen (1883-1962) and his wife Ella Kirstine Rasmussen (maiden name) (1892-1979).^[3]

He took his high school diploma at Marselisborg Gymnasium in 1933, and in 1942 he obtained a master's degree in arts from Aarhus University. Later, he held various teaching positions at the same university, until he became a professor of Nordic languages at Odense University in 1966. However, he returned to his former university in 1972.^[4]

He mostly devoted his attention to studying Danish dialects, especially the different dialects in Jutland and the history of the Danish language.^[5]

Niels Aage Nielsen was also a high-ranking communist member of the Danish resistance movement during the German occupation of Denmark.^[6]

• De jyske dialekter (The Dialects of Jutland). Copenhagen: Gyldendal 1959.
• Dansk etymologisk ordbog (Etymological Dictionary of Danish). Copenhagen: Gyldendal 1966, 6th edition 2010.
• Runestudier (Rune Studies). Odense: Odense Universitetsforlag 1968.
• Sprogets opståen og udvikling (The Origin and Development of the Language).(Søndagsuniversitetet 88). Copenhagen: Munksgaard 1968.
• Runerne på Rökstenen (The runic Letters on Rökstenen). Odense: Odense Universitetsforlag 1969.
• Dansk dialektantologi (Danish Dialect Anthology). Volume 1: Østdansk og ømål. Volume 2: Jysk. Copenhagen: Hernov 1978–80.
• Mellem jyske modstandsfolk 1941–1945 (Between Jutlandic Members of the Resistance Movement). Copenhagen: Zac 1980.
• Sprogrenseren H.C. Ørsted (The Language Cleaner Hans Christian Ørsted). Volume 1–2. Aarhus: Nordisk Institut, Aarhus University 1981.
• 50 danske runeindskrifter (50 Danish runic Inscriptions). Aarhus: Nordisk Institut, Aarhus University 1981.
• Syntaksen i Holbergs epistler (The Syntax in the Epistles of Holberg). Aarhus: Nordisk Institut, Aarhus University 1983.
• Danske runeindskrifter: et udvalg med kommentarer (Danish runic Inscriptions: A Selection with Comments). Copenhagen: Hernov 1983.
• Norske indslag i nydansk (Nordic Features in modern Danish). Volume 1: Dansk over for norsk sprog ca. 1700–1950. Volume 2: Liste over låneord fra norsk ca. 1700–1950. Aarhus: Nordisk Institut, Aarhus University 1983–84.
• Fra runesprog til nudansk: studier og kommenterede tekster (From runic Language to modern Danish: Studies and commented Texts). Aarhus: Nordisk Institut, Aarhus University 1984.
• (in collaboration with Hallfrid Christiansen) Norsk-dansk ordbog (Norwegian-Danish Dictionary). Gyldendal 1971.
• (in collaboration with Sven Brüel) Gyldendals fremmedordbog (Gyldendals Dictionary of foreign Words). Copenhagen: Gyldendal, 9th edition 1983.