William Pitt (4 June 1855 – 25 May 1918) was an Australian architect and politician. Pitt is best known as one of the outstanding architects of the "boom" era of the 1880s in Melbourne, designing some of the city's most elaborate High Victorian commercial buildings. He worked in a range of styles including Gothic Revival, Italianate, French Second Empire, and his own inventive eclectic compositions. He had a notable second career after the crash of the 1890s, becoming a specialist in theatres and industrial buildings.