Oscar Kreuzer (German pronunciation: [ˈɔskaʁ ˈkʁɔʏtsɐ]; 14 June 1887 – 1 May 1968) was a male tennis and rugby player from Germany.

[3] In 1912, he also reached the final at the World Hard Court Championships at Paris which he lost to his compatriot Otto Froitzheim.

[1] At the end of July 1914, he and Otto Froitzheim played the semifinal of the International Lawn Tennis Challenge at Pittsburgh against Australasia.

When World War I broke out, the president of the local tennis club kept this from Froitzheim and Kreuzer as he didn't want to disrupt the match.

[4][5][6] In 1920 he won the International German Championships at the Rothenbaum club in Hamburg, defeating Louis Maria Heyden in the final in three straight sets.