Prince Augustus Ferdinand of Prussia was a Prussian prince and general, as well as Herrenmeister of the Bailiwick of Brandenburg of the Order of Saint John. He belonged to the House of Hohenzollern, and was the youngest son of Frederick William I of Prussia by his wife, Queen Sophia Dorothea.

The Bailiwick of Brandenburg of the Chivalric Order of Saint John of the Hospital at Jerusalem, commonly known as the Order of Saint John or the Johanniter Order, is the German Protestant branch of the Knights Hospitaller, the oldest surviving chivalric order, which generally is considered to have been founded at Jerusalem in 1099.