Otto of Bavaria (His Majesty Otto Wilhelm Luitpold Adalbert Waldemar, King of Bavaria) (27 April 1848-11 October 1916) was the insane King of Bavaria from 1886 to 1913. He was the younger son of Maximilian II, King of Bavaria and his wife, formerly Marie of Prussia.

Because of his insanity, the constitution of Bavaria was amended on 4 November, 1913 to include a clause specifying that if a regency for reasons of incapacity had lasted for ten years with no expectation that the king would ever be able to reign, the regent could proclaim the end of the regency and the demise of the crown, with such action to be ratified by the parliament.

The following day, Otto was deposed by his cousin, Prince Regent Ludwig on November 5, 1913, by proclamation, who, as next in line for the throne, assumed the title Ludwig III. Otto was permitted to retain his title and honours. The parliament assented on 6 November, and Ludwig III took the constitutional oath on 8 November.