Ο William II Frederick (Wilhelm II Friedrich, 1744-1797) was King of Prussia from 1786 until his death in 1797. He was born in Berlin, the son of Frederick II and Louisa Amalia of Brunswick. He succeeded his uncle, Frederick II the Great, and took the throne at a time when Prussia was flourishing as a major European power.

His reign was characterized by efforts to strengthen the military power and administrative efficiency of the state. However, his rule was overshadowed by the French Revolution and the resulting changes in the political map of Europe. William II maintained an authoritarian stance and focused on strengthening the military and the finances of the state.

As far as Freemasonry was concerned, William II was a member and in particular was associated with lodges in Prussia, and was influential in the development of Freemasonry. Historical records confirm that he became a member of the Brotherhood, reflecting the important role the Brotherhood played among the European monarchs and intellectuals of his time.

He was associated with a Prussian lodge, probably related to the Große Landesloge von Preußen (Grand Lodge of Prussia). However, the specific details of the lodge or the ranks he held remain unclear in the available records. His membership provided legitimacy and protection to the Brotherhood, promoting its growth and cultural importance during his reign.

He died on 16 November 1797 in Potsdam.