The Passacaglia for Violin and Viola is a musical piece composed by Johan Halvorsen in the late 19th century and based on an earlier work by Georg Friedrich Händel.
Data, together with his "mother" Juliana Tainer performed the Passacaglia for Violin and Viola during a concert aboard the USS Enterprise-D in 2370. Data played the violin, Juliana Tainer the viola. (TNG: "Inheritance")