Joseph Lange was an actor and amateur painter of the 18th century. Through his marriage to Aloysia Weber, he was the brother-in-law of Wolfgang Amadeus Mozart.

His first marriage, in 1775, was to Maria Anna Elisabeth Schindler, daughter of Philipp Ernst Schindler, a miniature painter and director of painting at the Viennese porcelain factory. Maria Anna died on 14 March 1779 of pneumonia.

He married Aloysia Weber, a successful soprano, in Vienna on 31 October 1780. In that year he also agreed to support Aloysia's widowed mother Cäcilia with an annual payment of 700 florins.

Mozart married Aloysia's younger sister Constanze in Vienna in 1782, and thus became Lange's brother-in-law. The Mozarts and the Langes seem to have been friends, as the written record preserves various occasions that they socialized together, as did Wolfgang and Joseph individually. Both Lange and Mozart were Masons; see Mozart and Freemasonry.

In 1783, Lange performed in one of Mozart's works, a "Masquerade" (pantomime with music) composed for Carnival. The characters were traditional figures of the Commedia dell'arte, and the music was composed by Mozart (K. 446). Lange played Pierrot, and Mozart himself took the role of Harlequin.

In 1786, Lange appeared in another work by Mozart, his opera Der Schauspieldirektor. He took the spoken role of Herz, his wife Aloysia taking one of the two primary soprano roles, Madame Herz.

As of 1795, he lived separated from Aloysia. In 1808, he published his autobiography. From around 1800 on he lived together with a Therese Koch with whom he had three daughters.