Otto Nielsen (19 June 1909 – 9 October 1982) was a Norwegian songwriter, revue writer, cabaret singer and radio personality.

[3] The duo also produced children's programs for Trøndelag Kringkaster in Trondheim, and Nielsen co-wrote the first Norwegian operetta for radio, Postboks 39.

[3] Several singer-songwriters saw their first songs performed in this program, including Kari Bremnes, Birgitte Grimstad, Lars Klevstrand and Stein Ove Berg.

Nielsen composed the melody for Alf Prøysen's popular song Du skal få en dag i mårå (1966).

Nielsens and his sister Gerd (Røstad) made a re-recording of some of their best known songs in 1982, issued on the Polydor album Svanesang i stereo.