William Stanley, Jr. (November 28, 1858 - May 14, 1916) was an Americann physicist born in Brooklyn, New York.
In 1885, Stanley built the first practical alternating current device based on Lucien Gaulard and Josiah Willard Gibbs' idea. This device was called an induction coil. It was the precursor to the modern transformer. The induction coil that Stanley built was very primitive.