Johann Decker-Schenk (born 1826 in Vienna; died 23 August/4 September 1899 in St. Petersburg) was an Austrian guitarist, singer (tenor) and composer.
Johann Decker-Schenk learned to play the guitar from his father, the violin and guitar maker Friedrich Schenk, and later studied opera singing (tenor) at the Vienna Conservatory. He then gave concerts in Germany and England until 1861. After that, he moved to St. Petersburg. From 1866 to 1874, he was theatre director there. In 1870, he opened an operetta theatre with a French troupe that performed successfully in numerous cities in Russia. He gave concerts in Kiev with the Ukrainian doctor and guitarist Michael Vasilyevich Polupayenko (1848–1902). From 1875 to 1883, he lived in Tiflis. After the death of his wife, a singer, he returned to St. Petersburg in 1884 and gave guitar lessons. The instrument maker Julius Heinrich Zimmermann, also based in St. Petersburg, listed Decker-Schenk model coat of arms guitars in his instrument catalogue, which were only made to order.