Oscar Fetrás (16 February 1854 – 10 January 1931) was a German composer of popular dance music, military marches, piano pieces and arrangements.
He was regarded as the most talented light music composer that Northern Germany ever produced and from the start modelled his own composing on that of his idol, Johann Strauss Jr. As a gift of thanks for his waltz "Mondnacht auf der Alster" which brought Hamburg international acclaim, the local business community gave Fetrás a bronze statue of the Roman god Hermes/Mercurius by the French artist Marius Montagne.
This statue is the only remaining possession of Fetrás which survived the World War II bombings and is now owned privately in Henstedt-Ulzburg near Hamburg.
It might have been Franz von Blon, at that time the conductor of the Stadttheater Orchestra, who introduced "Mondnacht auf der Alster" at the inaugural concert for the 1888 ball season.
In 1904 he won a prize for his composition "Frühlingsluft" and later he wrote Reiche Mädchen, a reworking of Johann Strauss's 1897 operetta Die Göttin der Vernunft.
In 1943, the Uhlenhorster Fährhaus was destroyed by Allied bombing, and with it was lost the original score of Fetrás's most famous work "Mondnacht auf der Alster".