Durchlauchtster Leopold, BWV 173.1, is a secular cantata by Johann Sebastian Bach. Bach composed the cantata for performance in Köthen to celebrate the birthday of Leopold von Anhalt-Köthen. The cantata is one of a series of congratulatory works which Bach wrote for this employer. Some of them are lost, while others such as Der Himmel dacht auf Anhalts Ruhm und Glück, BWV 66.1 can be reconstructed because Bach reused the music later. Durchlauchtster Leopold is unusual in surviving in a complete state.

The cantatas composed by Johann Sebastian Bach, known as Bach cantatas, are a body of work consisting of over 200 surviving independent works, and at least several dozen that are considered lost. As far as known, Bach's earliest cantatas date from 1707, the year he moved to Mühlhausen, although he may have begun composing them at his previous post in Arnstadt. Most of Bach's church cantatas date from his first years as Thomaskantor and director of church music in Leipzig, a position which he took up in 1723.