Oscar Grégoire, Belgian water polo player and swimmer (d. 1947)
Oscar Grégoire (26 March 1877 – 28 September 1947) was a Belgian water polo player and backstroke swimmer who competed in the 1900 Summer Olympics, in the 1908 Summer Olympics, and in the 1912 Summer Olympics. He was part of the Belgian water polo team and was able to win two silver and one bronze medal. In 1908 and 1912 he also participated in the 100-metre backstroke events, but was eliminated in the first round in both.