William Joseph Hussey (August 10, 1862 – October 28, 1926) was an American astronomer.
He is most famous for the discovery and study of close binary stars. In the period from 1898 to 1899, he reobserved all binaries discovered by Otto Struve, with at least three observations of each. His amazing efficiency is demonstrated by these numbers: he made 1,920 observations in one year, with a record of 80 in one night. At the conclusion of his double star work in 1905, he had discovered and measured 1,327 close binaries. For this work, he was awarded the Lalande Medal in 1906, which he shared with Robert Grant Aitken.
In 1897, he was elected president of the Astronomical Society of the Pacific.
A crater on Mars was named in his honor.