Frederick William II (German: Friedrich Wilhelm II.; September 25, 1744 –  November 16, 1797) is King of Prussia, from 1786 until his death.

He is in personal union the Prince-elector of Brandenburg and (via the Orange-Nassau inheritance of his grandfather) sovereign prince of the Canton of Neuchâtel.

Pleasure-loving and indolent, he is seen as the antithesis to his predecessor, Frederick II.

Under his reign, Prussia is weakened internally and externally, and he fails to deal adequately with the challenges to the existing order posed by the French Revolution.

His religious policies are directed against the Enlightenment and aimed at restoring a traditional Protestantism.

However, he is a patron of the arts and responsible for the construction of some notable buildings, among them the Brandenburg Gate in Berlin.