William Badcock (1622–1698) was a London goldsmith and hilt-maker and also the author of a book on the gold and silver trade.
He was admitted to the Worshipful Company of Goldsmiths of London in September 1668, and was also a member of the Longbow String Makers' Company of London.
He was the author of an influential book, "A Touch-stone for Gold and Silver Wares", published in 1677, which was enlarged in 1679 as "A New Touch-stone for Gold and Silver Wares".
In the second edition, Badcock drew attention to the many fraudulent practices current in the trade at this period.
An example of his work - a sword with a hilt of cast and engraved silver and an etched blade (hallmark 1676–1677) can be found in Room 54b of the Victoria and Albert Museum.