Holger Louis Nielsen (18 December 1866 in Copenhagen – 26 January 1955 in Hellerup) was a Danish fencer, sport shooter, and athlete.

Nielsen defeated Adolf Schmal and Georgios Iatridis, but lost to Telemachos Karakalos and Ioannis Georgiadis.

[6] He won a bronze medal in the rapid fire pistol, coming in last of the three shooters that finished the competition.

[7] His best result of the Games was a surprise silver medal in the free pistol competition; his score of 285 was far behind Sumner Paine's 442 but was sufficient to defeat the other three shooters in the event.

[9] Together with fellow Københavns Roklub athlete Eugen Schmidt, Nielsen also participated in the unofficial football event in which a Danish XI faced a Greek team as a "demonstration sport", and it was the Danes who came-out as the winners by either 9–0 or 15–0.