Bjørn (Björn, Bjorn) Nielsen (4 October 1907 – 21 May 1949) was a Danish chess master.
He played for Denmark in Chess Olympiads:
He won individual gold medal at Munich 1936.
In 1933, he tied for 6-7th in Copenhagen (Politiken, Aron Nimzowitsch won), In 1941, he tied for 5-6th in Munich (Europaturnier, Gösta Stoltz won).
He was Danish Champion in 1941, 1942, 1944, and 1946. In 1947 he shared 1st, but lost the play-off to Jens Enevoldsen, 0.5 point against 3.5 points. He also shared 1st in 1949 but died in Herning before the play-off against Poul Hage could take place.