Magnus Nilssen (18 July 1871 – 20 November 1947) was a Norwegian politician for the Labour and Social Democratic Labour parties. He was born in Lillehammer as a son of shoemaker Mathias Nilssen (1834–1920) and his wife Eline Pedersen (1835–1918). He was a first cousin of . He finished his apprenticeship as a goldsmith in 1889, and moved to Kristiania in the same year. He was a secretary in his local trade union from 1891 to 1892 and treasurer in 1893. He was also member of the socialist youth club Friheden in both Kristiania and Sarpsborg (where he lived in 1894). He started his own goldsmith business in 1897. In November the same year he married Inga Marie Ravneberg.