The Siegfried Idyll is one of Richard Wagner's few non-operatic works. It was written as a birthday present to his second wife, Cosima. It was first performed on Christmas day (Cosima's birthday) in 1870, by a small ensemble on the stairs of their villa Tribschen in Lucerne in Switzerland. Today, it is often performed by orchestras.

The title refers both to the Wagners' son Siegfried (who had been born in 1869) and Wagner's opera Siegfried (which was not premiered until 1876), from which the piece draws several motifs.