Maximilian III Joseph (28 March 1727 – 30 December 1777), also known by his epithet "the much beloved" was a Prince-elector of the Holy Roman Empire and Duke of Bavaria from 1745 to 1777.

After the decisive defeat in the Battle of Pfaffenhofen on 15 April Maximilian Joseph quickly abandoned his father's imperial pretenses and made peace with Maria Theresa in the Treaty of Füssen, in which he agreed to support her husband, Grand Duke Francis II Stephen of Tuscany, in the upcoming imperial election.

None of his 15 doctors could diagnose it, but by Christmas, it had become clear that it was a particularly virulent strain of smallpox, called "purple small pox" at the time.

He was succeeded (in the male line) by his 12th cousin, once removed, the Elector Palatine Charles Theodore from the senior branch of the dynasty.

of Prussia and the new elector's presumptive successor, Charles II August, Duke of Zweibrücken, to secure Bavaria's independence from Austria.

Instead, Charles Theodore, much to public annoyance, repeatedly tried to change it for Further Austria or the Austrian Netherlands, even better, for proximity to his Palatinian homelands.

Wolfgang Amadeus Mozart was received by Maximilian III Joseph, who was like his sister Maria Antonia Walpurgis of Bavaria skilled in music and composed, but due to a need for strict frugality no post could be offered.

In 1775 La finta giardiniera, an Italian opera by Wolfgang Amadeus Mozart, received its first performance at the Salvatortheater in Munich.